DISCUSSION OF SPECIES AND THEIK DISTRIBUTION. 477 



be made to keep it eutire, btit that it .should be cut into sliort leuj^tlis mid preserved iu the 

 strongest spirits, each piece wrapped separately iu uuislin. 



Giiuther (Challenger Keport, xxii, 72) gives a very satisfactory summary of the present 

 state of knowledge iu regard to the variations of TnuliyxUaun at diflereut periods of 

 growth. 



TRACHYPTERUS, Gouan. 



Trnchypierus, Coi-aN, Hist. Toiss., 104, l.'iB.— Cuvikr, Rtgue Animal, vA. 2, 1829. u, 24,-).— CuviER and Vai.ex- 

 ciENNES, Hist. Nat. Poiss., x, 313.— GiNTHKU, Cat. Fish. Bnt. Mus., ui, 300; Challenger Kt-port, xxii, 72. 

 Bogmani/i, ScHNEiDEK, Bloch, Syst. Ichth., 1801, 518. 



Trachypterids having the body elongate, compressed, ribaud-sluiped, the dorsal fin 

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

 ent, bnt sometimes absent. Ca\ulal present and placed for the most part above the longi- 

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



The veutrals appear to be absent iu some individuals, but Day calls attention to tlie 

 fact that most of the specimens of T. arcticn.s taken along- the coa.st t)f Great Britain have 

 had no veutrals. In the very y<iung, as has been shown by Emery, the tin rays commence 

 to grow when it is about (J m'iliimeters long, and continue to lengthen until it is about 24 

 millimeters long, after which a partial shortening takes place. The veutrals are very elou- 

 o-ate iu the young, and the caudal rays much longer than in the grown fl.sh. 

 '^ Young "individuals (from 2 to 4 inches) are not raiely met with near the surface; they 

 possess the most extraordinary development of tin rays observed iu the wluile chiss of 

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

 like dilatations. There is no doubt that tishes witli sucli .lelicate appendages are bred and 

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

 the surface would deprive them at once of organs wliieh must be of some utility lor their 

 preservation. 



PROVISIONAL KEY TO THE ATLANTIC AND MEDITERRANEAN SPECIES. 



(Adapted from Morean.) 



I. Lower line of body straight. 

 A. Dorsal rays 160. 



1. Dorsal rays smooth. .j, ^^p^ipj.g 



n. Height of body i5i in length T Ri ppelh 



h. Height of body 8Un length ,j, j j^^j,,^,.^,.,, 



c. Height of body 0-10 in length 



2. Dorsal rays rough. 



a. Lateral line .spinous. .j,^ ^^.^^ 

 'Height of body 4-10 in length 



h. Lateral line smooth. ,j, ^kyi-hubus 



' Height of body 5i in length 



II. Lower line of body irregular, sinuous. 



A. Dorsal rays less than 130. T. fRiSTAxre 



1. Lateral line spiny - • -p^ kepakdl'S 



III. Anterior dorsal and ventral rays much prolonged 



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



Fair Venetorum, Belox. 



Cepola trachypfera, Gmelin, Linn. Sy.st. Nat., 1788. 1187. 



Cepohi iris, Walbaum, Artedi, in, 017. crxcvil -GCnther, Cat. Fi.sh. Brit. Mus., 



Trcwh,,pten,s iri., Cuvier and Valenciennes, op. ,./., x, oil, pi. ccxc^ ii. 



r„, 303.-MOREAU. Hist. Nat. Poiss mnce, IK 50.).-^-.-^^^.^^ ,,,^^^,_ ,., ,,._p„,,. 



Trachypterus iama, Schneider, Bloch, Syst. I''^''^' '**"''.''*";, '.,.^^.,. ... y.,,,^., nalica. Pcsci., 113.-GI- 

 PARTE, Catalogo Metodico, No. 711.-GrNTHER. toe. «r.-CANK.lKi.M, launa 



GLioLl, Eleuco, loc. at. . i-._Hist. Nat. Eur. Merid., ui, lS2ti, 295. 



(lymuelnis cepediamis, Ris.so. Ichth. Nice, 1810, 10, pi- ^. *■'.,• 

 Epidesmus maculatus, Ra^nzani, Opusc. Sci. d'ltalia, ii, liA. 



