Dr. A. 8. Woodward — Ichthyosaurus showing Embryos. 44-^ 



IT. — On two Specimens of Ichtiiyosaurus showing contained 



Embryos. 



Ey A. Smith Woodward, LL.D., F.R.S. 



(PLATE XXIV.) 



Tj'^OR many years it lias been known that Ichthyosaurus was » 

 Jj viviparous reptile/ bnt until quite recently the British Museum 

 has not possessed a specimen with contained embryos. This 

 deficiency has now been supplied by the acquisition of two fine 

 skeletons, which are worthy of special notice. 



The first of these newly acquired specimens (PI. XXIV, Fig. 1) 

 is of much historic interest, because it was discovered and described 

 so long ago as 1846 by the late Dr. J. Ghaning Pearce, a well-known, 

 pioneer in Palaeontology.^ It was obtained from the Lower Lias of 

 Somersetshire, and appears to belong to the species I. communis. The 

 skeleton is nearly complete, and is exposed from the right side, 

 though partly from below. The ribs and paddles of the right side 

 are displaced upwards; and the tail is dislocated, though clearly 

 exhibiting the downward flexure of its terminal portion. The single 

 embryo, as described by Ghaning Pearce, lies between the two sides 

 of the pelvis, crushed on the three hindmost ribs. Its head points 

 backwards, but is flattened by crushing, and does not show any 

 structural details. The vertebral centra are small biconcave discs of 

 spongy bone, not arranged in continuous series but somewhat 

 scattered. The head of the embryo, so far as preserved, measures. 

 0"04 m. in length, while the remains of the trunk extend for another 

 length of 0-105 m. The total length of the parent is about 2-25 m.^ 

 that of the head being 0*5 m. Although its precise dimensions 

 cannot be determined, the embryo in this individual is therefore 

 relatively smaller than in the other known specimens. 



The second Ichthyosaur with embryos received by the British 

 Museum (PI. XXIV, Fig. 2) was obtained from the Upper Lias of 

 Holzmaden, Wxirtemberg, and is referable to I. quadriscissus, which 

 has been provisionally identified by Mr. Lydekker with I. acutirostrin.^ 

 This is the species to which all the best specimens displaying embryos 

 belong. The skeleton, which measures about 2*4 m. in length, is 

 well preserved and exposed from the right side, the right ribs only 

 being displaced upwards. The black contents of the stomach are 

 clearly shown in the lower part of the abdominal region. There 

 are remains of at least six embryos within the ribs, but some of them 

 have been displaced forwards, either by post-mortem crushing or by 

 escape into the body-cavity during life (as happens occasionally in 



' H. G. Seeley, " Eeport on the Mode of Eeproduction of certain species of 

 Jchthi/osanrus from the Lias of England and Wiirtemberg " : Eep. Brit. Assoc, 1880 

 (1881), pp. 68-76, pi. i. E. Fraas, " Die Iclithyosaurier der siiddeutschen Trias- und 

 Jura-Ablagerungeu " (TUbingen, 1S9I), p. 34, pi. iv, fig. 2. 



2 J. Chaniug Pearce, ' ' Notice of what appears to be the Embryo of an Ichthyosaurus- 

 in the Pelvic Cavity of Ichlhyosnurus [comnmnis ?) " : Ann. & Mag. Nat. Hist., 

 vol. xvii (18)6), pp. 44-46. 



» K. Lydekker; " Catal. Fuss. Kept. B.M.," ^jt. ii (1889), p. 73. 



