^{page 489 note 1} Lyttelton, , Phil. Trans. 1750, vol. xlvi. p. 598, pl. i. and ii.;Google Scholar Mortimer, ibid. p. 600; Mendez da Costa, ibid. 1753, vol. xlviii. p. 296; also Guettard, Wilckens, Klein, Walch, Beckmann, etc., 1757 to 1773.

^{page 489 note 2} Brongniart and Desmarest, Hist. Nat. Crust, foss. 1, pl.i.Google Scholar

^{page 489 note 3} Four parts hare already appeared, with upwards of 30 plates and above 700 figures, together with descriptions of 114 species of Trilobites.

^{page 490 note 1} “Hall, in his 'Palæontology of New York,' has figured the lenses. I have never seen any traces of them.”—J.W. S.

^{page 490 note 2} This little specimen was sent me privately in a letter by Mr. Gray, some long time since, and, to my regret, I am unable at this moment to light upon it, or I should have figured it on the accompanying plate.

^{page 490 note 3} Mr. Gray informs me that for fifty years the miners have not only collected and developed Trilobites, but even made them when they did not turn up in sufficient abundance. He adds, “New and undescribed species are still to be purchased, composed of parts of Calymene and Phacops united together, either by accident or by the aid of a knife and a little gum.” I have myself seen (in the possession of Dr. Grindrod, of Malvern) an Ampyx nudus cleverly made out of the limestone with the help of the tail of a Phaeops Downingiæ.

^{page 491 note 1} For the original figures and description of this remarkable species of Asaphus, see Article XI. “Zwei Neue Asaphus-arten aus dem Silurischen Kalksteine des Gouvernements St. Petersburg,” von N. Lawrow. Taf IV. and V., p. 239, in the Verhandlung. der Russisch-k. Mineral. Gesell. zu St. Petersburg, Jahrgang, 1855–1856.Google Scholar

^{page 491 note 2} In Bell's British Slalk-eyed Crustacea this has actually been done, but of course the Stomapoda are a perfectly distinct group.

^{page 491 note 3} The original specimens are preserved in the British Museum.

^{page 492 note 1} In the 4th edition of Murchisson's “Siluria” (p. 357), a figure is given of the ordinary form of Asaphus expansus, Wahl., in which the eyes are quite sessile, and not all all elevated above the glabella, as represented at Fig. 3 in our Plate. Another example there figured, called variety cornutus, has its eves more elevated than in our Fig. 3, but less so than in Figs. 4 and 5, Pl. XXI. The eyes in this front view are seen to diverge laterally, as in our Calymene certophthalma.Google Scholar

^{page 492 note 2} From κéраѕ, a horn: and, 'Οϕθυλμòѕ, the eye=horn-eyed.

^{page 493 note 1} Among the Araehnida there is a little spider in the genus Wakhencera W. acuminata, the male of which has a tall and slender central fixed peduncle, upon which the eyes are placed, two at the summit and four midway on either side.