^{page 32 note 1} The North American Crinoidea Camerata. By Wachsmuth, C. and Springer, F.. Mem. Mus. Comp. Zool. Harvard, vols. xx and xxi, containing 838 pp. and 83 plates. (Cambridge, U.S.A., 05, 1897.)Google Scholar For First, Second, Third, and Fourth Notices, see GEOL. MAG. for June, July, September, and November, 1898.

^{page 32 note 2} Miller and Gurley, 1890 = Ceriocrinus White pars, 1880, non Desor, 1845, nee Königintabb. ineditis.

^{page 37 note 1} Wachsmuth and Springer are wrong in thinking that I ever denied the general homology of x with any plate in the Camerata. in a passage, which they tjuote almost accurately, I once said, “it may be pointed out that, as interradials do not enter into the composition of the dorsal cup in any Fistulate, none of these [anal] plates can well be the homologues of interradials:inmany of the Camerata actual interradials are present in the anal area, but in the Fistulata at least we must look elsewhere for the origin of the so-called [anal] plates” (Ann. Mag. Nat. Hist. [6], v, p. 319).Google Scholar Having regard to the meaning at that time attached to the term ‘interradials,’ it is clear that this merely meant that the anals of Fistulata could not have been developed by the modification of interradials, since no such elements preexisted in that suborder, whatever might have been the case in Camerata. As to the course of evolution in Ichthyocrinidae and the Camerata I said plainly (op. cit., p. 331)Google Scholar “I can express no opinion.” It should have been impossible to inter from this that “Bather makes no reference to the anal plates of the Ichthyocrinidse, but regards the anals of the Camerata as morphologically distinct from those of the Fistulata … because they [Fistulata] possess no interbrachials.” Again, I said that one had no right to regard the anal plate of Antedon as a mere interradial when there were no such plates in the other interradii. Wachsmuth and Springer seem to think this nonsense (p. 139); yet in the very next paragraph they say that the “large interradial plate” on which rests the anal tube of Thaumatocrinus “is not a special anal, for a similar plate is interposed between the radials of the other four sides.” But this is the precise and legitimate converse of the very argument that they ridicule.

^{page 38 note 1} Ann. Mag. Nat. Hist. (6), vol. v, pp. 319–334.Google Scholar

^{page 38 note 2} Proc. Acad. Nat. Sci. Philadelphia, vol. for 1890, pp. 345–392.Google Scholar

^{page 38 note 3} Ann. Mag. Nat. Hist. (6), vol. vii, pp. 480–489, 06, 1891.Google Scholar

^{page 38 note 4} Ann. Mag. Nat. Hist. (6), vol. ix, pp. 64–66, 01 1892.Google Scholar

^{page 38 note 5} Loc. cit. ult.

^{page 38 note 6} In reply to their present assertion (p. 128) that they had always regarded the proximal posterior plate of Iocrinus and Merocrinus “as a plate of the tube,” and had “never made any statement from which he might infer that we thought it represented the plate x; yet he quotes us in his diagrams as if we had done soin1879,” it is enough to say thatinplate xvi of their “Revision of Palæocrinoidea,” 1879, the letters an are applied equally to the median line of tube-platesinIocrinus, to the plate which they now and always have homologized with the proximal of those median platesinAnomalocrimis and Hybocrinus, and to the plate x of Cyathocrinus. With this before me, why ou earth should I have introduced into a diagram doubts that had never occurred to me or anyone else ?

^{page 41 note 1} Since I utilized this fact as an argument, "Wachsmuth and Springer have persisted in denying its truth and have stigmatized my diagrams as incorrect. If it was not true, why did theyin“Revision of Palæocrinoidea,” iii, pp. 206, 207,Google Scholar write thus:—inEctenocrinus the r. post, “radial … upon its upper side supports the brachials, giving off laterally a small ventral tube”; and,inHeterocrmus “the smaller radial is transversely pentagonal, and resemblesinoutline a bifurcated plate [axillare]. It supports upon its sloping right side the brachials; toward the left the ventral sac asinIocrinus.” ? My diagram of Heterocrinus was, as stated at the time, taken from the drawing of H. bellevillensis by W. R. Billings, whose description isincomplete accordance with the foregoing remarks, as pointed outin“Crinoidea of Gotland, I” (1893), p. 72.Google Scholar I have no hesitation in saying that this mode of description is absolutely correct. I have most courteously been given the opportunity of studying a very large series of specimens of Heterocrinus and allied genera from the Trenton Limestone in the Walcott collection at the Museum of Comparative Zoology, Harvard.inthese x is invariably closely attached to r. post. Rs, although in many specimens it is clearly separated from 1. post. R.inseveral the RR have become separated from one another, probably by pressure, and, when the posterior interradius is the one exposed, it is always seen that the line of division passes to the left and not to the right of x. This proves (so far as the consistent testimony of hundreds is to be held as proof) that the union between x and r. post. R is much stronger than that between x and l. post. R, even though the geometrical relations of the two radials to x may occasionally be similar. But x rarely does lie

symmetrically to the adjacent radii: it is nearly always towards the right of the interradius; its two sides abutting on r. post. Rs and its IBr₁ are straight and meet almost at a right angle, whereas the side or sides abutting on l. post. R and its IBr₁ generally form a continuous curve rather than an angle;inall cases where there is any swelling of the radials, or any development of axial folds, then x is clearly connected with the swelling or fold of r. post. R, andinno way with that of l. post. R (Fig. 17). These statements, which may be verified by anybody, refer specially to the Heterocrinidae, though many of them hold good for species not in that family.

^{page 41 note 2} “Wachsmuth and Springer again criticize my application of the term ‘axillary’ to the r. post. Rs of Iocrinus. They take no notice of my explanation (“Brit. Foss. Crin. III,” Ann. Mag. Nat. Hist. [6], vi, 09 1890, p. 228).Google Scholar But there is more to be said for the application than I was then aware of. The accompanying drawings (Fig. 18) were made from specimens of Iocrinus subcrassus in the Mus. Comp. Zool. Harvard. I shows the inferradial, superradial, and first brachial of the r. post, radius from inside; the anal tube is broken off, but its ventral groove is seen passing down the Rs and coalescing in the Ri with the ventral groove of the arm. II shows the articular surface of Ri with the dorsal ligament-fossa, the two muscle-plates, and the already dividing ventral groove. Ill and IV show the two upper articular surfaces of Rs, III on the left, bearing the median proximal anal, IV on the right, bearing the first brachial;ineach are to be seen the dorsal ligament-fossa, two muscle-plates and fossæ, and a wide ventral groove merging into a narrow tongue where the axial cord lay. These facts prove: (1) that r. post. Rs was united to the proximal anal in the same way as to IBr₁; (2) that the anal mid-rib was innervated by the same axial cord as was the r. post. arm. From which we infer (1) that the proximal analinIocrinus actually is “a plate corresponding to an ordinary brachial”instructure; (2) that the mid-rib may have arisen as a branch of r. post, arm; (3) that, in any case, the application of the term axillare to r. post. RsinIocrinus is warranted by something more than the “angularity which occurs upon the upper face,” “the form of the plates succeeding it to the left, and the slanting the posterior arm to the right” (W. & Sp., p. 129).

^{page 43 note 1} “Calamocrinus Diomedœ”: Mem. Mus. Comp. Zool. Harvard, vol. xvii, No. 2, 01 1892; see p. 36. The adjoining figures are adapted from this marvellously detailed work.Google Scholar

^{page 43 note 2} Carpenter, P. H., “On a new Crinoid from the Southern Sea”: Phil. Trans., 1883, pt. iii, pp. 919–933, pl. lxxi; see pp. 925, 930.Google Scholar

^{page 44 note 1} “Brit. Foss. Crin. II”: Ann. Mag. Nat. Hist. (6), vol. v (04, 1890); see pp. 322, 324.Google Scholar

^{page 44 note 2} “The Perisomic Plates”: Proc. Acad. Nat. Sci. Philadelphia, vol. for 1890, 02 1891; see pp. 389, 390.Google Scholar