MUR.ENlDiE. 137 



one dirocted backward. The vent is nearly always very small, and, 

 in preserved examples, at least, it cannot alwaj-s be discovered. Its 

 position is variable, even in examples entirely similar in other 

 points. Air-bladder none. No trace of generative organs. 



The vertical fins, when present, are confluent, vtdth more or less 

 conspicuous traces of rays ; sometimes they are merely a fold of the 

 skin, without any rays. Pectoral fins sometimes present, sometimes 

 rudimentary, sometimes entirely absent. Ventrals none. 



Most examples have series of round black dots along each side of 

 the abdominal profile, along the lateral line, and sometimes along 

 the dorsal fin. They remind us of the phosphorescent dots of many 

 Scopehdte, Stomiatidce, and other pelagic fishes. 



These fishes are found floating in the sea, frequently at a great 

 distance from the land. Their movements are slow and languid. 

 The largest specimen of Leptocephalns observed by me is 10 inches ; 

 but specimens of that size are very rare. 



Prof. J. V. Carus has given an account of the organization of 

 these fishes in a separate pamphlet, ' Ueber die Leptocephaliden,' 

 Leipzig, 18G1, 4to, from his own examinations, as well as from 

 those of Prof. Kiilliker. Considering tlie low organization, the em- 

 bryonic condition of these creatures, the numerous variations of 

 form and development of the several organs, the total absence of 

 organs of reproduction. Cams came to the conclusion that they are 

 nothing but early stages of development of other fishes, Leptocephalus 

 perhaps of Cepola, TUurus perhaps of Trichiunis. 



Altliough this view of Prof. Cams deserved every consideration, 

 the suggestion of a possible identity of Leptocepiludus ^\'ith Cepola 

 was so obviously erroneous that his conclusions generally were re- 

 ceived with suspicion, until Mr. Gill expressed his unqxialified belief 

 that the Leptocephalides are merely larval forms (Proc. Ac. Nat. 

 »Sc. Philad. 18(54, p. 207). By his extensive ichthyological know- 

 ledge lie was enabled to arrive more nearly at the truth with regard 

 to their determiuation. He declared the typical Lcp>toccphaVi , at 

 least, to be the young of Congers, and L. morrisii the young of 

 Conger vulgaris ; Ht/oprorus is referred to Nettastoma ; whilst he is 

 imcertaiu about Stomiasuncidus and Esunculiis. TUurus is not 

 mentioned in the short note about the subject. 



I have fully convinced myself of the correctness of Mr. GiU's views 

 with regard to L. ^norrisii and Hijoprorus ; and I may add at once 

 that I consider Stomiasunndus to be a young Stomias, and Esunculus 

 probably a young Alepoccphalus. It is not likely that TUurus is an 

 Apodid ; the presence of pseudobranchise and ■n'idth of the gill- 

 openings leads me to suppose that it will prove to be an Acantho- 

 pterj'gian or Anacanthine fish. 



Mr. Gill has not given the reasons which induced him to regard 

 L. morrisii as a young Conger. Beside the similarity in the form of 

 llio head and its parts, 1 may draw attention to the coincidence in 

 the number of vertebra? (loii) and geographical distribution. The 

 ^iimilarity in the form of the snout and position of the nostrils be- 



