ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 301 



The early stages of development occur in the oviduct ; and in eggs 

 freshly laid the visceral clefts are present, and the first rudiment of the 

 limbs is discernible. As there are great practical difficulties in obtain- 

 ing gravid females, the early stages of development were not observed 

 in very great detail. The observations were throughout confined to the 

 development of the external characters. In regard to the development 

 of the harl palate, some interesting points were made out. The first 

 trace of this structure is a triangular plicated swelling at either side of 

 the maxilla — a condition which may be compared to that which is per- 

 manent in the Gecko among lizards. In the course of development 

 in the crocodile the structure gradually passes through the stages 

 represented in the other lizards ; but while in the lizards the internal 

 nares may lie at the posterior border of the palatines, they never come 

 into relation with the pterygoids as in living crocodiles. In these 

 therefore the posterior nares gradually move backwards, successively 

 occupying the positions seen in fossil forms, until they ultimately reach 

 the typical position. At the time of hatching the jaw of the embryo is 

 furnished with a strong bifid callosity, which is made of dentine and is 

 not merely a horny structure. It appears at the end of the first month 

 of incubation, and persists for some days after hatching. The paper 

 also discusses the development of various other external morphological 

 structures. 



Ovarian Follicles of Reptiles.* — Miss Marie Loyez has investigated 

 the structure of the ovary in certain lizards and Ophidians, and finds 

 that the follicles consist of two kinds of cell: — (1) ordinary follicular 

 cells, and (2) large cells which are apparently aborted ova, and which 

 appear to assist in the formation of yolk. The egg grows at the expense 

 of these cells, the process recalling the conditions seen in many inver- 

 tebrates. It is of interest to note that normal eggs exercise a phagocytic 

 action upon these follicular cells; but degenerating eggs, on the other 

 hand, yield to the phagocytic activity of the follicular cells, thus exactly 

 reversing the normal conditions. 



External Features in the Development of Lepidosiren paradoxa 

 Fitz.f — Mr. J. Graham Kerr finds that the papillas on the hind legs 

 of the male Lepidosiren rapidly develope at the breeding season into 

 slender vascular filaments, and that the main axis of the limb also 

 enlarges. He considers that the main function of this modified struc- 

 ture can scarcely be other than respiratory. The coelomic egg, which 

 is of a pale salmon colour with a whitish germinal cap, measures from 

 about 6 to 7 mm. in diameter, and is enclosed in a transparent capsule 

 about 1 mm. thick. As found in the nest — an underground burrow at 

 the bottom of the swamps of the Gran Chaco — the egg is enclosed in a. 

 horny capsule, and in some cases is invested by a jelly-like secretion 

 comparable to that found in Amphibia. Segmentation is complete and 

 unequal, closely resembling that of Amia. Invagination begins over 

 about one-third of the entire extent of the boundary between small and 

 large cells ; but, owing to the flattening out of the lateral parts, the 

 blastopore is only about one-fourth of the original slit. The archeu- 



* Coraptes Rendus, cxxx. (1900) pp. 48-50. 



t Phil. Tians., Series B, cxcii. pp. 299-330 (5 pie.). 



