Several investigators have contributed to our knowledge of the development of the chondrocranium in various mammals, amongst whom Decker (1883), Gaupp (1900), Noordenbos (1905), Fawcett (1905) and Voit (1909) are the most outstanding. No attempt has as yet been made to study the chondrocranium of the camel however, due without doubt to lack of suitable material.

Development of the nasal capsule in ungulates generally has been studied in detail only by a few workers. Strum (1937), for instance, investigated the fully developed chondrocranium of Bos, while Decker (1883) and Wincza (1896) give accounts of the primordial skull of Ovis only at a particular stage in development.

Accordingly, this investigation is an attempt to describe for the first time, as far as the author can determine, the nasal capsule of the chondrocranium in Camelus dromedarius.

A large number of density measurements of the more important rock-types exposed at the surface in Ayrshire and certain neighbouring areas provide information for the interpretation of gravity measurements. The three methods employed of determining density are (1) laboratory measurements of rock samples, (2) gravimeter measurements in mineshafts, and (3) gravimeter measurements over topographic features.

The first method, the most widely used, is the only one applicable to many of the geological formations. A total of 600 specimens measured cover all the common rock types of the Lower and Upper Palaeozoic systems and their associated igneous rocks. Use of the second method is restricted to Carboniferous rocks, in which records from four mine-shafts—Littlemill 5, Mauchline I, Auchincruive I, and Houldsworth—cover much of the Carboniferous succession in south Ayrshire. The third method was seldom applied as there are few suitable topographic features, independent of geological structure, in Ayrshire.

The results of the measurements are summarized, and their reliability discussed. Two contrasts of rock density of regional importance occur in the sedimentary succession of south Ayrshire—the first at the plane of unconformity between Upper and Lower Old Red Sandstone, and the second between Lower Old Red Sandstone and the Lower Palaeozoic greywackes. A marked contrast of local importance occurs between the Permian sandstones of the Mauchline Basin and the underlying lavas and Carboniferous rocks. In north Ayrshire the most important density contrast lies between the Upper Palaeozoic sediments and the associated dense igneous rocks—the Clyde Plateau Lavas, the Millstone Grit lavas, and the thick dolerite intrusions.

In the Sanquhar district a bsain of relatively light Upper Carboniferous rocks (relative density 2·54) overlies a denser basement of Ordovician greywackes (relative density 2·72). A gravity survey over the area with coverage of approximately one station per square kilometre, increasing to a station spacing of 100 yards along certain traverses in critical localities, shows a close relation between the Bouguer anomalies and the known geology. A local gravity low over the Carboniferous outcrop is superimposed on a steep regional gradient decreasing south-eastwards. The trend of this gradient is parallel to the strike of the Ordovician rocks, but its exact relationship to the basement structure is not clear. The residual Bouguer anomalies reflect the structure of the Carboniferous rocks; in the south-eastern part of the basin they agree closely with the calculated effect produced by the known thicknesses, structure, and density contrast. Westwards from Kirkconnel, however, there is an increasing discrepancy between the observed and the theoretical anomalies, a discrepancy which indicates the presence of an additional mass of light rock concealed under the known Coal Measures. It is inferred that this material consists of older Carboniferous strata, thickest under the present-day valley of the Nith but concealed by overstep of the overlying Coal Measures against the flanks of the basin. These hidden rocks thin gradually to the south-east across a shallow monocline with north-east trend and south-east of Kirkconnel are truncated by a large fault trending east-north-east. Both the monocline and the fault appear to affect the Westphalian strata to a lesser degree than the base of the Carboniferous rocks.

The stratigraphical significance of the concealed strata is that they evince the existence of a pre-Westphalian basin, trending north-west-south-east, which antecedes the later Hercynian fold, and also suggest that pre-Hercynian movements took place along a fault, near Kirkconnel which, trends north-east-south-west across the basin.

Heteropneustes (Saccobranchus) fossilis Bloch. is a common airbreathing fish found in India. It possesses a respiratory sac on each side of the body embedded in the lateral myotomes. The structure of this organ, its respiratory function and the phenomenon of “drowning” when the fish is denied direct access to the air have engaged the attention of several workers in the past among whom Day (1868), Dobson (1874), Burne (1896), Das (1927), Hora (1935) and Marlier (1938) deserve mention. The only detailed account of the structure of the accessory organ of this fish is available to us from the work of Das (1927) who also paid some attention to its development. Dobson (1874) and Hora (1935) mainly concerned themselves with some experiments bearing on the “drowning” of the fish when compelled to live under water. Little information is obtainable from the existing literature on the following points which have an important bearing on evolution of its accessory respiratory organs:

(i) the gross and minute structure of the respiratory sac, especially its vascularization;

(ii) the origin and derivation of the accessory respiratory organs (=the “Fans” and the respiratory sac); and

(iii) the muscles concerned with its breathing movements.

Details are given of two more Giant Squids (Architeuthis) found in the Scottish area. The question of which species occur is discussed. It is suggested that the two species, A. harveyi Verrill and A.princeps Verrill, described from the American side, do not occur on the European side, as certain identifications would suggest. The two species found on the European side would, therefore, be A. dux Steenstrup and A. clarkei Robson.

Electron micrographs of the anterior part of the mid-gut and hepatic cæca of Blatta orientalis Linn, show epithelial cells in both secretory and absorptive cycles. The epithelial cells possess microvilli and their lateral margins are provided with irregularly shaped projections that interdigitate with neighbouring cells. Vacuole-like structures were observed in association with the mitochondria of absorptive and degenerating cells. These vacuoles, it is suggested, represent degeneration products. Bundles of saccules and associated groups of vacuoles and vesicles represent the Golgi rods and granules of light microscopy. Epithelial cells engaged in absorption differ from those in which the elaboration of secretion is taking place, in the arrangement of the Golgi saccules and vacuoles, in the size of the Golgi vacuoles, in the distribution of the mitochondria, and in the possession of a less extensive endoplasmic reticulum.