350 Mr. A. S. Woodward on Rhapliiosaurus. 



pigment-circulation. The discharge of pigment, however, is 

 something different and possibly capable of a very different 

 interpretation. 



Is the discharge normal or abnormal? Is it a result of 

 extraordinary conditions under which the animal is placed in 

 confinement in our aquaria, or is it an habitual mode of pro- 

 tection ? It seems to me that the latter interpretation will 

 best satisfy our limited knowledge ; and although when the 

 bracts are broken the discharge is more voluminous, since the 

 glands are wholly emptied of their contents, the method of its 

 discharge shows it to be a function which is perfectly normal. 



It seems to me that we have in these " glands " the homo- 

 logues of nematocysts, the thread of which is wanting and the 

 cells of the interior of which have degenerated or rather 

 specialized into pigment-bodies, instead of functioning as an 

 urticating-thread. These modified nematocysts throw off a 

 coloured fluid which, while it serves in a similar way in pro- 

 tection or in killing its prey, bears little morphological like- 

 ness to the well-known lasso-cell. 



XLV. — On the so-called Cretaceous Lizard, Rhapliiosaurus. 

 By A. Smith Woodward, F.G.S., F.Z.S., of the British 

 Museum (Natural History). 



In 1840 Prof. Sir Richard Owen described a small portion of 

 mandible from the Lower Chalk of Cambridgeshire under the 

 name of Rhaphiosaurus *, regarding the fossil as referable to 

 a Lacertilian Reptile and provisionally associating with it a 

 series of undoubted Reptilian vertebrse from the Lower Chalk 

 of Burliam, Kent. Ten years later the vertebrge proved to 

 pertain to a distinct generic type named Dolichosaurus f ; and 

 the original jaw thus remained as the sole evidence of the 

 existence of Rhaphiosaurus. In 1865 Prof. Seeley { stated 

 incidentally that the specimen so determined probably belonged 

 to a fish ; and still more recently the genus has been recorded § 

 as one requiring further elucidation. 



* E. Owen, " Description of the Vertebral Column &c. of a small 

 Lacertine Saurian from the Chalk," Trans. Geol. Soc. [2] vol. vi. (1840) 

 p. 413, pi. xxxix. fig. 3. MhapMosaurus suhulidens, Owen, Brit. Assoc. 

 Rep. 1841, p. 190. li. lucius, Owen, in Dixon's 'Geol. Sussex' (1850), 

 p. 385, pi. xxxix. figs. 1-3. i?. subuUdens, Owen, " Foss, Rept. Cret. 

 Form." (Pal. Soc. 1851), p. 19, pi. x. figs. 5, 6. 



t I-!. Owen, " Foss. Rept. Cret. Form." (Pal. Soc. 1851), p. 22. 



X H. G. Seeley, Ann. & Mag. Nat. Hist. [3] vol. xvi. p. 145. _ 



§ Smith Woodward, " A Svnopsis of the Vertebrate Fossils of the 

 English Chalk," Proc. Geol. Assoc, vol. x. (1888) p. 281. 



