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Show 46 MR. A. D. IMMS ON THE DENTICLES [Jan. 17, pharynx and extend backwards to the junction of the latter with the oesophagus. No denticles, however, extend on to t e branchial arches, and the junction of the mucous membrane covering the latter with that of the pharynx is clearly denned, as the denticle-covered area ceases very abruptly. As the specimen examined measured only 27 cm. in length, this condition is probably owing to the denticles not having yet attained then ru development. Fam. T orfedinid,e . 16. T orpedo 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. R ajid,®. 17. R aja clavata L.-In a young specimen, 30 cm. long, very minute denticles were found irregularly distributed over the 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. T rygontd^e . 18. T rygon walga Mull. & Henle. - Oral and pharyngeal denticles were totally absent in an example of this species measuring 47 cm. long. Fam. M yltobatid.e . 19. M yliobatis aquila L.-In a specimen 40 cm. long oral and pharyngeal denticles were likewise totally absent. C. H o l o c e p h a l a . 20. C him.era monstrosa L.-In two examples of this fish, one of which measured about 60 cm. to the tip of the tail, no traces of denticles were to be detected in any part of the mouth oi pharynx. To this list may be added two species, examples of neither of which have been examined by Steinhard nor by myself, viz.: - Alopias vulpes (Fam. Lamnidse) and Echinorhinus spinosus (Fam. Spinacidse). Dr. Popta * in a recent paper entitled " Les Appendices des Arcs Branchiaux des Poissons," which deals with the gill-rakers and pharyngeal armature of Teleostomes, has some remarks on these two Elasmobranchs. With regard to Alopecias he says :__" Les arcs n'ont pas d'appendices et, il n'y a pas des dents pliaryngiales, mais les hordes larges et la partie superieure de la * Ann. Sci. Nat., Zool. t. xii. 19C0, pp. 139-216. |