Z.D, 



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XVII. On the Structure and Development of the Skull in the Crocodilia. 

 By W. K. Paekek, F.R.S., F.Z.S. 



Received October 15th, 1881, read January 17th, 1882. 



[Plates LXII. to LXXL] 



Introduction. 

 Several years ago I received from my friend Mr. David Bartlett several ripe young 

 embryos of a Crocodile, the species of which was undetermined. Other ripe embryos 

 of Crocodihis acittus (from St. Domingo) were about the same time given to me by 

 another friend, Mr. Henry Power, F.E.C.S. 



For about twelve years no further addition was made to my collection, nor further ob- 

 servations recorded than such as were done, partially, soon after receiving these treasures. 



But early in the summer of 1879 I received from my talented young friend, 

 Mr. Henry F. Osborn, of Princeton, U. S., a box of the eggs of Alligator mississipensis. 

 These had been laid quite recently, and contained nothing sufficiently advanced 

 for my purpose ; but soon afterwards, when this failure had been made known 

 to Mr. Osborn, I received another box of eggs. These reached me on August the 

 8th ; they were twenty-six in number, and all but one of them yielded me embryos. 



These have served me for my earlier and most important stages ; but the largest 

 embryos were scarcely half ripe. 



Shortly afterwards I received a large number (several dozen) of embryos of Croco- 

 dilus palustris S from Dr. Kynsey, P. M. O. of the Hospital, Colombo, Ceylon, who 

 took great pains for me, employing his native assistant, Mr. S. Waytialingam, to collect 

 them. This zealous service I owe to the influence of Sir Joseph Fayrer. An account 

 of the nest-rifling of these " fearful wildfowl " has already appeared in the ' Proceed- 

 ings ' of this Society (1880, pp. 186, 187). There were about eighty of these 

 embryos, ranging from If to 10 inches in length; they were most carefuUy preserved 

 and tabulated. 



I have no dates in the case of the embryos of the Alligator, and I can therefore only 

 give measurements ; but in the Crocodile embryos the time is given in each case, and 

 this in specimens taken from two places, namely, Vadunakaloo and Talavaikal ; the eggs 

 from both these sources were evidently laid about the same time. Mr. Waytialingam 

 says that they are laid as early as June ; and as the smallest specimen measured nearly 

 2 inches in total length, and was taken on the 16 th of July, it is probable that both 

 the nests were filled by the middle of June. They were ripe on the 8th of September, 



' See GUnther's ' Reptiles of British India,' p. 61, pi. 8. fig. a. I must here call the reader's attention to the 

 extreme heauty of the plates (by G. H. Ford) both in that work and in Dr. Gray's paper referred to on the 

 nest page. 



VOL. XL — PAET IX. No. 1. — Octobcr, 1883. 2t 



