1888.] SELACHIAN MORPHOLOGY, 127 



name S. sahel-almre. It is an undoubted member of the Seyl- 

 liidse ; the vertebral centra are distinctly asterospondylic ; the 

 body is much depressed, so that all the fossils display either the 

 dorsal or ventral aspect ; the tail is very long ; the teeth are of the 

 orcUiiary type ; and some other disti ictive features are shown. lu 

 one respect, however, it seems to diff.-r from all known Scylliidae. 

 It is destitute of dermal shagreen ; and on this account the 

 peculiarity to be here noted is very conspicuous in the impressions 

 upon the limestone. 



On either side of the trunk and tail, at a short distance from the 

 vertebral column, there is a delicate longitudinal streak, which, 

 upon close examination, is found to consist of a series of minute 

 ringlets, in their crushed state overlapping one another. Though in 

 some parts obscure, these are very distinctly shown to be incomplete 

 half-rings, and they are thus precisely similar to those already 

 described by Leydig in Chimcera, and by myself in Squaloraja. 

 They occupy the position of the lateral line in the fossil, and they 

 are of the usual proportions, s-o that there can be no doubt as to the 

 correctness of their identification. They are especially evident in 

 one specimen in the British Museum, numbered 4810" ; but neither 

 in this, nor in any other, have I observed an extension of the rings 

 upon the cephahc region, a circumstance perhaps indicating that, 

 as in Chimcera, the groove of the lateral line was partially closed in 

 its anterior portion. 



Whatever may be the significance of the facts just detailed, they 

 are worthy the attention of biologists having the opportunity of 

 examining the anatomy of recent Selachians. It is quite possible 

 that the supports of the lateral line of Sci/llium sahel-almce are a 

 surviving mark of affinity with the Chimseroids ; it is equally 

 possible that they may relate only to analogous mechanical contin- 

 gencies. Further observations upon the characters of the "lateral- 

 line" structures in Selachians with naked skins are much to be 

 desired. 



II. On the Pelvic Cartilage o/Cyclobatis. 



One of the most remarkable endoskeletal structures presented for 

 consideration among extinct Selachians, is the pelvic cartilage of a 

 small Sting-Ray {Cyclobatis), from the prolific Cretaceous fish-beds 

 of Mount Lebanon. This does not appear to have been hitherto 

 correctly interpreted, and as it may eventually prove to have a not 

 unimportant bearing upon certain theoretical considerations, a brief 

 description and separate figure will doubtless be acceptable to 

 biologists. The fish was originally described as a fossil Torpedo by 

 Egerton ', but I have lately determined that it is almost certainly 

 referable to the Trygonidae ^. 



As shown in the accompanying woodcut (p. 128) the transverse 



^ Sir P. Egerton, "Description of a Fossil Eay from Mount Lebanon 

 {Cyclobatis oUgodactylus)," Proc. Geol. Soc. vol. iv. pp. 442-446, pi. v. 



^ Smith Woodward, " Note on the Affinities of the so-called ' Torpedo ' from 

 the Cretaceous of Mount Lebanon," Geol. Mag. [3] vol. iv. 1887, pp. 508-510. 



