ON THE llKi'ltOUlJCTlO-N OF CERTAIN SrECIES OF IClITIITOSiAUriUS. G9 



• Anatomy of the Vertebrates ' so far hesitated about the true nature and 

 classification of Ichthyosaurs as to speak of them in one place (vol. i. p. 

 50) as Dipnoa, although as a rule they are arranged with the Monopnoa. 

 So far as I can learn, there is no evidence in support of Prof. Haughton's 

 hypothesis that Ichthyosaurs pass through a metamorphosis. _ But, on the 

 conti-ary, a number of examples, British and foreign, enforce a conviction 

 that several species of the genus brought forth their young alive. In all 

 cases they appear to have been retained in the body of the parent till a 

 compai-atively large size had been reached. Attention was first drawn to 

 this characteristic of the genus by the late Dr. Chaning Pearce, of Bath, 

 who, in 1846, contributed to the 17th volume of the ' Annals of Natural 

 History,' a paper entitled ' Notice of what appears to be the Embryo of 

 an Ichthyosaurus in the pelvic cavity of I. communis.' In his note it is 

 stated that the large animal from the Lias of Somerset is about eight and a 

 half feet long. The little animal lies at full length in the pelvis, with its 

 head directed towards the tail of the large one, and is supported upon the 

 internal surface of its integument and upon the internal sui'faces of three 

 posterior ribs of the left side. The young animal measured five and a half 

 inches in length. The rami of the jaws and one of the longest ribs, of 

 which only five or six are visible, are each an inch long ; and of the thirty 

 vertebrae which can be counted the largest measures an eighth of an inch 

 in its longest diameter. 



This minute specimen is bounded on each side by the ilium, ischium, 

 and pubis, and by the right and left posterior paddles, and on the right 

 side by the vertebral column and ribs which extend from it. The pos- 

 terior two-thirds of the little animal is within the pelvis, but the head 

 appears to protrude beyond it, and was apparently in the act of being 

 expelled at the time of death. The late Dr. Chaning Pearce remarks on 

 the correct position of this minute skeleton in the pelvis between the right 

 and left ribs, with the head protruding ; and from the exact correspondence 

 between its bones and those of the large Saurian draws the inference that 

 it can only be a foetal Ichthyosaurus. During the meeting of the Biitish 

 Association in Bath in 18G4, it was my good fortune to have an oppor- 

 tunity of studying this specimen, and it enforced in my mind the same 

 inference that was enunciated by its discoverer. Its perfect condition of 

 preservation, size, and position in the body seem to me completely to 

 refute the current opinion of those days when Dr. Pearce's conclusions 

 Avere not accepted, that the young animal might have been swallowed 

 whole, and have gradually found its way to the position in which it 

 was fossilized. This view Dr. Chaning Pearce combated by remarking 

 that had so delicate a structure been swallowed whole it could not have 

 reached its present place without being dissolved by the gastric juice. 



Among the series of Ichthyosaurs presented to the Woodwardian 

 Museum, by Thomas Hawkins, Esq., is a large slab with the remains im- 

 perfectly preserved, but containing a disturbed skeleton of a young Ich- 

 thyosaur in the pelvic region. The vertebral column has the vertebree in 

 sequence, and the head is remarkable for the high form common in embryos 

 (fig. 1). Taken by itself no inference as to the mode of reproduction 

 could fairly be drawn from this fossil, but as a link in a chain of evidence 

 it has some value. A third British specimen is said to have occurred in 

 the Lias of Lyme Regis, and to have shown a number of embryos in the 

 pelvic cavity. I have not seen this specimen, but Mr. Henry Keeping, who 

 first reported its existence to me, considered that it was altogether incon- 



