NATURAL SCIENCES OP PHILADELPHIA. 207 



arrested my attention, there being six or seven narrow bands, the lateral 

 line running through the fourth ; the interval between the two dorsal bands 

 was more indistinct, and the two could readily be confounded ; the width of 

 the two would equal about a sixth of the height, while the width of the sin- 

 gle ones was contained about fifteen or sixteen times in the height. The two 

 lower bands were more indistinct. I was therefore at once reminded of the 

 Trichhirvs lepturus of Hoy, and the similar development of the bars, as 

 well as the approximation in proportions, compel me to believe that the sec- 

 ond specimen of Hoy is in reality a species of the genus Evoxymetopon, if not 

 indeed identical with the Cuban fish itself, (Evoxymctopon txrtiaius Poey.) 

 The greatest height of the latter, at the scapular region, is contained scarcely 

 more than twelve times (12 l-5lh) in the extreme length, while a short dis- 

 tance behind, and for a considerable distance, it is contained from thirteen 

 and a half to fourteen times. The head enters eight times and a half, and 

 the caudal, at its longest rays, twenty-nine times and a half in the same. 

 The anus is midways between the snout and root of caudal. In this last re- 

 spect it disagrees with the specimen signalized by Hoy, according to whom 

 the anus was very considerably within the limits of the first third of the 

 length (46 : 153 + ) Such a position is extremely improbable in a repre- 

 sentative of the sublamily of Lepidopodinae, to^which the specimen doubtless 

 btlongs. The true anus, on account of its small size, was probably over- 

 looked, and a rupture of the skin mistaken for it. May we not hope that 

 some British naturalist will soon release us from our doubts, and verify the 

 systematic position of Hoy's fish? 4 



POLYPROSOPUS Couch. 



Having provisionally adopted the generic name Polyprosopus, proposed by 

 Couch, in the " Analytical Synopsis of the Order of Squali," remarking at the 

 same time that the genus was "not yet well established," it seems advisable 

 now to express my conviction that it belongs to the genus Cetorhinus or Selache, 

 and that the differences observed are probably due to distortion or defective 

 observation. I have already stated that "the absence of caudal carinas or 

 spiracles is quite improbable," and certainly no scientist could believe in the 

 absence of the anal fin in such a type. 



I may finally be permitted to add, in anticipation of a more extended 

 memoir, remarks on the Lemniscates of Richardson, and more especially the 

 Leptocephaius Morrisii Gm. The recent exposition of the character of such 

 fishes, by Professor V. Carus,* will excuse this anticipation. I am happy to 

 be able to express my unqualified belief in the conclusion as to their being 

 simply larval forms, which that learned naturalist has enunciated. As long 

 as the known hyaline fishes conformed to a single type, naturalists might be 

 excused for regarding them as fully developed forms, but the doubt this group 

 was first subjected to by the failure of Kollikerf to find organs of generation 

 was increased by the addition by Kaup of the genus Esunculus,\ and subse- 

 quently of Stomiasunculus.fy Carus was therefore, I think, fully justified in 

 his "conclusion that all these fishes are nothing but larval forms of others," 

 but he was not so happy in looking for the auults " among the Ophidians, or 

 other compressed forms, (Cepola, and so on.)" I am almost certain that 

 the typical Leptocephali, at least, are the young of Congers, and that Leptoceph- 

 aius Morrisii is the young of Conger vulgaris. I am aware, indeed, that Yar- 

 relll| has discovered that small congers, " about the size (length?) of a man's 



* Carus "on the Leptocephalidae," in Rep. Br. Ass. 1861, p. 125. 

 f KoUiker, Zeitschrift fur Wiss. Zool. iv., p. 360. 

 J Kaup, Apodal Fishes, 1856, p. 143, fie. 3. 

 Kaup, An. Mag. N. H. (3) 1860. p. 270. 

 jj Yarrell, Br. Fishes ii., 1841, p. 404. 



1864.] 



