REPTILES. 93 



borders, and rounded at the smaller ends. 1 According to my measurements, the proportion of its 

 length to its breadth = 1 to 4 in Angius fragilis, in Ophisaurus ventralis = 1 to 3'2, in Pseudopus 

 Pallasii = 1 to 2'5. Its proportion to that of the whole body is only very small ; for even in Pseudopus 

 Pallasii, in which I found it to be greatest, its length is to that of the whole body only as O02 to 1. 

 The structure is cartilaginous, of which the greater part, though not all, is ossified. In Ophisaurus the 

 plate is cartilaginous, at all its edges especially, and for a considerable depth at its posterior sharp edge ; 

 in Anguis at its anterior and posterior edges, though to a less extent ; in Pseudopus only at its poste- 

 rior edge, and to a slight extent. The ossified part exhibits a cartilaginous basis with low powers, and 

 appears at its surface, on account of little knobs, somewhat uneven when the bone has been dried. 

 These granules liave roundish, or oval, or frequently irregular, forms, lie moderately close together in 

 Pseudopus, but less close in Anguis and Ophisaurus, and measure O0030 of an inch. If the thin 

 sternal plate of Anguis fragilis be examined under the microscope, it will be found that at the outer 

 surface of its anterior and posterior cartilaginous borders only very small and simple cartilaginous 

 cells are present, but nearer the deep or attached border of the cartilage the cells attain a larger size, 

 and contain two or four or, though rarely, six daughter-cells in their interior ; and further, each of the 

 granules above mentioned as existing on the surface of the bony plate consists of a group of such 

 enlarged cartilage-cells, filled with a brood of others, the walls of which are penetrated with lime salts. 

 The walls of these ossified mother-cells of the cartilage have sharp outlines, a smooth surface, and are 

 so thin and transparent that the contents of the contained daughter-cells (which is a soft, slightly 

 granular substance), besides the remains of the nuclei, can be distinctly perceived. 2 If the sternal 

 plate be divided, there may be seen on the cut surfaces, in each of the ossified mother-cells that have 

 coalesced with one another and with the ossified walls of the daughter-cells, one, two, or three very 

 thin and perfectly smooth septa traversing it, so that the space included by each mother-cell appears to 

 be divided into two or more chambers. I have not observed either indentations or outrunners (cana- 

 liculi) on the walls of these chambers, which might have extended from the surface of the ossified 

 mother-cells into the intervening matrix. The above-described compound bony cells are arranged at 

 distances of about 0'0025 of an inch, and even in the thickest part of the sternal plate are only in 

 rows of three or four deep. 



The material which occupies the intervening spaces is of about the same consistence as the matrix 

 of cartilage, and when fresh and moist appears semi-transparent and homogeneous. When dry, however, 

 numerous fine calcareous granules are seen, making it appear as though it were permeated by fine fibres in 

 various directions. Upon the whole, it is only very incompletely ossified, and from this . circumstance, 

 as well as from its thinness, still remains pliable. A structure essentially similar to that seen in Anguis 

 fragilis is possessed by the plate or larger piece of the Sternum in Pseudopus Pallasii. The compound 

 bone-cells, however, which constitute the greater part of the mass, have a diameter of 0-0040 inch, and 

 also have somewhat thicker walls than in the Blind-worm. 



The other or smaller piece of the Sternum [inter-clavicle'] is so placed beneath the larger that 

 it extends, though to an insignificant amount, forwards beyond the border of the latter. In Anguis 



J. Miiller found in Pseudopus Pallasii the posterior border of the Sternal plate convex (see 

 above reference, pi. xix, fig. 2) ; on the other hand, R. Wagner depicts it slightly concave (' Icones 

 Zootom./ p. xiii, fig. 26). The form of the plate, therefore, appears to vary in Pseudopus to some 

 extent. 



' These compound ossified cells have an appearance generally similar to those represented by 

 Kolliker in the second volume of his ' Microscopic Anatomy,' 1850, at fig. 95, as taken from the 

 os pubis (Schambeinfiige) of Man, but lie somewhat closer. 



