46 MR. A. D. IMMS OX THE DEXTTCLES [Jan. 17, 



pharynx and extend backwards to the junction of" the latter 

 with the oesophagus. No denticles, however, extend on to the 

 branchial arches, and the junction of the mucous membrane 

 covering the latter with that of the pharynx is clearly defined, as 

 the denticle-covered area ceases very abruptly. As the specimen 

 examined measured only 27 cm. in length, this condition is pro- 

 bab\v owing to the denticles not having yet attained their full 

 development. 



Fam. ToRPEDixic.B. 



16. Torpedo ocellata Rudolphi. — In two examples of this 

 species, each of which measured a little over 30 cm. long, no 

 denticles were to be detected over any part of the lining of the 

 mouth or pharynx. 



Fam. Rajid.e. 



17. Raja clavata L. — In a young specimen, 30 cm. long, very 

 minute denticles were found irregularly distributed over tlie 

 mucous membrane of the branchial arches and the adjacent 

 portions of the roof and floor of the pharynx. The denticles 

 are spine-like in form and have relatively large basal plates. 

 Vide PI. III. fig. 6. 



Fam. Trygoxtd^. 



18. Trygox walga Mull. & Henle. — Oral and pharyngeal 

 denticles were totally absent in an example of this species 

 measuring 47 cm. long. 



Fam. MrLiOBATiD.*:. 



19. Myliobatis aquila L. — In a specimen 40 cm. long oral 

 and pharyngeal denticles were likewise totally absent. 



C. Holocephala. 



20. CniMiEaA moxstrosa L. — In two examples of this fish, one 

 of which measured ahout 60 cm. to the tip of the tail, no traces 

 of denticles were to be detected in aiiy part of the mouth or 

 pharynx. 



To this list may be added two species, examples of neither of 

 which have been examined by Steinhard nor by myself, viz. : — 

 Alopias imljMs (Fam. Lamnidae) and EchinorJiinus spinosus (Fam. 

 Spinacidge). 'Dr. Popta* in a recent paper entitled ^' Les Appen- 

 dices des Arcs Branchiaux des Poissons," which deals with the gill- 

 rakers a,nd phar_yngeal armature of Teleostomes, has some remarks 

 on these two Elasmobranchs. With regard to Alojyecias he 

 says : — " Les arcs n'ont pas d'appendices et, il n'y a pas des dents 

 pharyngiales, mais les hordes larges et la partie supei'ieure de la 



* Anil. Sei. Nat., Zool. t xii. 19C0; pp. 139-216. 



