DISCUSSION OF SPECIES AND THEIR DISTRIBUTION. 477 



be made to keep it entire, but that it should be cut into short lengths and preserved in the 

 strongest spirits, each piece wrapped separatelj in muslin. 



Gunther (Challenger Report, wit. 72) gives a very satisfactory summary of the present 

 state of knowledge in regard to the variations of Trachypterus at different periods of 



grow th. 



TRACHYPTERUS, Gouan. 



Trachypterus, Gouan, Hist. Poiss., 104, 153. — CuvnsH, Regne Animal, ed. 2, 1S20. n, 215. — Cdvieb and Valen- 

 ciennes, Hist. Nat. Poiss., \. 313. — Ccnther, Cat. Fish. Brit. Mus., in, 300; Challenger Report, xxu, 72. 

 Bogmarw, Schneider, Bloch, Syst. Ichth., 1801, 518. 



Trachypterids having the body elongate, compressed, riband-shaped, the dorsal fin 

 extending the entire length of the hack. Anal absent; each ventral well developed, if pres- 

 ent, but sometimes absent. Caudal present and placed for the most part above the longi- 

 tudinal axis of the body. No air bladder. Pyloric appendages numerous. 



'I'lie ventrals appear to be absent in some individuals, but Day calls attention to the 

 tact that most of the specimens of T. arcticus taken along the coast of Great Britain have 

 had no ventrals. In the very young, as has been shown by Emery, the tin rays commence 

 to grow when it is about <» millimeters long, and continue to lengthen until it is about 24 

 millimeters long, after which a partial shortening takes place. The ventrals are very elon- 

 gate in the young, and the caudal rays much longer than in the grown fish. 



Young individuals (from li to 4 inches) are not rarely met with near the surface; they 

 possess the most extraordinary development of fin rays observed in the whole class of 

 lishes. some of them being several times larger than the body, and provided with lappet- 

 like dilatations. There is no doubt that fishes witli such delicate appendages are bred and 

 live in depths where the water is absolutely quiet, as a sojourn in the disturbed water of 

 the surface would deprive them at once of organs which must be of some utility for their 

 preservation. 



PROVISIONAL KEY TO THE ATLANTIC AND MEDITERRANEAN SPECIES. 



(Adapted from Morean.) 



I. Lower line of body straight. 



A. Dorsal raj s 160. 



1. Dorsal raj s smooth. 



a. Height of bod j 5J in length T. arcticus 



6. Height of body si m length T. Ri ppelii 



i. Height of body !t-10 in length T. liopterus 



2. Dorsal raj s rough. 



a. Lateral line spinous. 



Eeight of body 1-10 in lengih T. iris 



b. Lateral line smooth. 



" Height of body 5A in length T. GRYPHURUS 



II. Lower linn of body irregular, sinuous. 

 A. Dorsal rays less than 130. 



1. Lateral line spiny T. CRISTATD8 



III. Anterior dorsal and ventral rays much prolonged T. REPANDU8 



TRACHYPTERUS IRIS, (Walb.), Cuv. and Val. (Figure 391.) 



i'nl.r Venetorum, Belqn. 



Cepola traehyptera, Gmelin, Linn. Syst. Nat., 1788, 1187. 



Cepnlii iris, Waxjsaum, Artedi, III, (517. 



Trachypterus iris, Cuvier and Valenciennes, op. cit., x, 341, pi. ccxevn. — Gunther, Cat. Fish. Brit. Mas., 

 in. 303. — Moreatj, I list. Nat. Poiss., France. n,560. — Gii.lioli, Elenco, 32. 



Trachypterus Uznia, Schneider, Bloch, Syst. Ichth., 1801, 480.— Costa, Fauna Napolitana, pi. IX. — Bona- 

 parte, Catalogo Metodico, No. 711. — Gunther, loc. cit.— Canes ikini, Fauna Italics, Pesci., 113.— Gl- 

 olioi.i, Elenco, loc. cit. 



Gymnetrus cepedianus, kiss,,, ichth. Nice, 1810, 1 16, pi. v. Fig. 17.— Hist. Nat. Eur. Mend., m, 1826, 235. 



Epidesmus maculatus, RaNZANI, Oposc. Sci. d'ltalia, u, 133. 



