5.)(i 



SCAN! ) I.N" A VI AN FISHES. 



all tlu' older qicciinens the I);ise of the anal tin is greater 

 Than the distance between this tin and the tip of the 

 snout. This is also the case in the ln)ur-l)earded Roek- 

 liiii;': lint in the voung specimen of the Fi\e-bearded 

 Koekling, as well as in the Three-bearded and the 

 Xorthern IJocklings. the base of this tin is less than 

 the said distance. The almost uniform size of the jaw- 

 teeth in the Rve-bearded Koekling is a persistent ju- 

 venile character, which this species possesses in common 

 with voung specimens of the Three-bearded Rockling; 

 but the card of teetli on the head of the vomer is 

 never so broad in the tormer as in the latter, although 

 it does not undergo so great reduction as in the Four- 

 bearded Koekling. 



Die Five-Bearded Koekling thus ranks as an inter- 

 mediate form between the preceding ones, as we have 

 al)ove found to be the case with Onos fusciis in its 

 relations to On. mediferranciis and On. tricirratus. That 

 the original form of the whole genus was three-bearded 

 seems highly probalile, as the difference between the 

 unpaired and the paired arrangements of the rostral 

 barbels, presupposes a stage of develo})ment in which 

 this difference did not exist. In other respects, how- 

 ever, Onos niustela forms a connecting link between 

 tlie two directions of development, and mav, therefore, 

 in all probability be regarded, to the best of our know- 

 ledge, of the genus in its present arrangement, or at 

 least of the North Atlantic and the Mediterranean spe- 

 cies, as the least differentiated (most nearly original) 

 type witiiin the genus. 



In the Five-Bearded Rockling the coloration is of 

 a more or less dark reddish brown or even olive-green 

 on the dorsal side, liaht ^ravish, white, vellowish, oi* 

 sometimes reddish on the bellv, witliout any sharp line 

 of demarcation and without true spots. Sometimes, 

 however, we tind indistinct, clouded spots on the sides, 

 caused by the denser agglomeration of the fine, dark 

 In-oAvn dots that are scattered over the whole body. 

 The sides of the body show a metallic — or silvery — 

 lustre. The second dorsal tin ar the base is of the 

 same colour as the back, the anal tin as the belh', but 

 the outer and esi)ecially the posterior parts of these fins 

 are blackish. The pectoral tins are also blackish, but 

 of a more or less distinct orange at the base. At the 

 extreme margin all these tins are usually edged with 

 red. The nasal and rostral barbels are of the same 

 colour as the dorsal side or still darker, the barbel 

 under the chin of the same colour as the bellv. 



During life the ventral tins are reddish (Hollbehg), 

 or ha^■e "orange ravs, with w hitish-^■ello^\• membrane" 

 (ScHAGEUSTROJi). The "small iilack dots which are 

 set in oliliiiue rows across the sides' (Hollbehg), are 

 the pigmented dermal coverings of the several scales, 

 an ordinary characteristic of the Avhole of this genus, 

 which statement also applies to the tine, dark brown 

 dots that are scattered over the bodv. In a live vounif 

 specimen 78 nnn. long Collett found the pupil to be 

 of a handsome emerald-green, and thi; iris red, with a 

 metallic lustre. 



In tlu' fry {Courhia ulaiua ~Yh\\e XXVII, fig. 3), 

 which have lieen most fullv described, under the name 



Fig. 133. Young Onos. nnn. lung, with projecting lower jaw. 



After M'lsTO.SH and Prince, p, pectoral tin; c. ventral tin; (/ and c, 



the still continent dorsal and ano-caudal fins. 



of Mofelki (irf/ri/fcdld. l)v v. Dubex and Korex, the 

 back is bluish green do\vn to a level with the upper 

 corners of the gill-o])enings, and forms a sharp contrast 

 to the Avhite, silverv lustre of the sides. All the fins 

 are transparent and white, except the ventrals (tig. 134), 

 the black tip of which grows more and more indistinct, 



S^a?:5^-x 



^j3jT3;;~^gS^y-^ 



Fig. 134. Yonng Onos. 10 mm. long, with black tip to the ventral 



fins. After M'Intosh and Pkince. p, pectoral fin: c, ventral fin; 



rl, dorsal fin; c, caudal fin. 



however, as the tins are shortened during growth, and 

 their insertion removed further and further forward, 

 until in specimens about 'Ih mm. long these tins are 

 also iHire white. The development is subject to extreme 

 variations; but the scales do not appear until the tish 

 is about 38 nun. long, while the strong, silverv lustre 

 is still persistent, until the rish has attained a length 

 of 40 — 4."i mm., and even then, as we have remarked 

 above, does not disappear entirely, (^n the other hand, 

 the dermal carina t]iat runs on each side of the l)ack 

 from the end of the first dorsal tin along the base of 

 the second dorsal, as well as the similar carina on each 



