5i6 NATURAL SCIENCE. sf.pt.. 



affinities of these extinct reptiles with the primitive Rhyncho- 

 cephaHans (of which the sole remaining representative is the Tuatera 

 Lizard — Sphenodon — of New Zealand). Dr. Fraas is, however, by no 

 means thereby prepared to accept the view that Ichthyosaurs, 

 Rhynchocephalians, and Lizards should be regarded as constituting 

 one great branch of the reptilian tree. Seeing, however, that he 

 admits the probable origin of these reptiles from a primitive Rhyncho- 

 cephalian, the cause of his hesitation to adopt this view is not very 

 apparent. That the Ichthyosaurs have sprung from a stock which 

 was originally terrestrial, and hence occupy a position among reptiles 

 precisely similar to that held by the Whales among mammals, Dr. 

 Fraas fully endorses. 



In regard to the author's resume of the structure of the Ichthyo- 

 saurian skeleton, we have but one point to mention. This relates to 

 the bones forming the palate, in regard to the interpretation of which 

 there has been some difference of opinion. While adopting the view 

 taken in the British Museum Catalogue of Fossil Reptiles, that the 

 pair of bones occupying the middle of the palate in advance of the 

 pterygoids are the vomers. Dr. Fraas, as shown in plate ii. of his 

 memoir, considers that the bony bars flanking the two latter severally 

 consist of an anterior moiety identified with the palatine, and a 

 posterior moiety corresponding with the transpalatine or transverse 

 bone. It is true that in the skull figured by Dr. Fraas from Sir R. 

 Owen's plate there appears to be a division in this bar, but we strongly 

 suspect this is due to fracture ; and there is none in the type skull 

 of /. zetlandicns figured by Professor Seeley. Moreover, the position 

 of the palatines entirely in front of the posterior nostrils would be 

 quite abnormal. We have accordingly no doubt but that the whole 

 of these bony bars are the palatines. 



Many of the considerations relating to the probable mode of 

 life of the Ichthyosaurs referred to by our author cannot fail to 

 command attention; but the supreme interest attaches to the evidence 

 in favour of the viviparous reproduction of at least some of these 

 reptiles. It has been long known that certain large skeletons of 

 Ichthyosaurs from the Upper Liasof Holzmaden,in Wurttemberg,and 

 elsewhere, are found with the skeletons of one or more much smaller 

 individuals enclosed partly or entirely within the cavity of the ribs 

 as shown in our figure. Of such skeletons there are four in the 

 museum at Stuttgart, two in that of Tubingen, one at Munich, and 

 others in Gent and Paris (Fig. 2). Of these, two in Stuttgart, as well 

 as the two in Tubingen, contain but a single young skeleton, while one 

 of those at Stuttgart has four, the Munich specimen five, and the 

 remaining Stuttgart example upwards of seven young. Some of 

 these young and, presumably, fcetal Ichthyosaurs have the head 

 turned towards the tail of the parent, while in others it is directed 

 the other way. That these young have not been swallowed by 

 the larger individuals within whose ribs they are found, is pretty 



