DISCUSSION OF SPECIES AND THEIR DISTKIBUTION. 477 



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

 strongest spirits, each piece wrapped separately in musliTi. 



Giiiither (Challenger Report, xxii, 72) gives a very satisfactmy summary of the present 

 state of knowledge in regard to the variations of Trachyincrus at tliffereut periods of 

 growth. 



TRACHYPTERUS, Gouan. 



Trachi/pterus, GoUAN, Hist. Poiss., 104, 153. — Cuvier, Ri'gnt* Animal, ed. 2, 1829, il, 245. — CuviER and Valen- 

 ciENNE.s, Hist. Nat. Poiss., x, 313. — Gunthbk, Cat. Fish. Brit. Mus., Ill, 300; Challenger Eeiiort, xxii, 72. 

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



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

 extending the entire length of the back. 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. 



The ventrals appear to be absent in .some individuals, but Day calls attention to the 

 fact that most of the specimens of T. nrcticiis taken along the coa.st 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 (i 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, aud the caudal rays much longer than in the grown fish. 



Young individuals (from 2 to 4 inches) are not rarely met with near the surface; they 

 possess tlie most extraordinary development of flu rays observed in the whole class of 

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

 like dilatations. There is no doubt that tislies with such delicate appendages are bred and 

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

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

 preservation. 



PKOVISIONAL KEY TO THE ATLANTIC AND MEDITERRANEAN SPECIES. 



(Adapted from Moreau.) 



I. Lower line of body straij^lit. 



A. Dorsal rays 160. 



1. Dorsal rays smooth. 



n. Height of body 5i in length T. arcticus 



6. Height of body 8+ iu length T. RiPPELll 



<: Height of body 9-10 in length T. mopterus 



2. Dorsal rays rough. 



a. Lateral line siiinons. 



-Height of l)Ocly 4-10 in length T. nus 



b. Lateral line smooth. 



" Height of body 5i In length T. gryphurus 



II. Lower line of boilv irregular, sinuous. 



A. Dorsal rays less than 130. 



1. Lateral line spiny T. cristatus 



III. Auterior dorsal and ventral rays much prolonged T. REPANDUS 



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



Fair Veneiorum, Belon. 



Cepola trachyplera, GjrELiN, Linn. Syst. Nat., ITS.**, 1187. 



Cepohi iris, Walbaum, Artedi, in, 617. 



Traclnjplenis iris, CuviER and Valenciennes, op. cif.,x,3il,pl. ccxcvil. — GxJnther, Cat. Fish. Brit. Mus., 

 Ill, 303. — Moreau, Hist. Nat. Poiss., France, ii, .560. — Gigliou, Elenco, 32. 



Trachjipterits ta'nia, Schneider, Bloch, Syst. Ichth., 1801, 480. — Costa, Fauna Napolitaiia, ]>I. ix.— Bona- 

 parte, Catalogo Metodico, No. 711. — Gi'NTHER, loc. cit. — Canestkini, Fauna Italica, I'esci., 113. — Gl- 

 GLIOLI, Elenco, loc. cit. 



Giimnetrits ccpeclianiis, Risso, Ichth. Nice, ISIO. 116. pi. v, Fig. 17.— Hist. Nat. Eur. Mcrid., Iii, 1826, 235. 



Epidcsmiis macitlatua, Kajszani, Opusc. Sci. d'ltalia, ii, 133. 



