918 



SCANJJIXAVIAN FI.SIIES. 



Kspos. intern. Pesca, Berlin 1880. Sez. Ital., p. 102) + 



Ary. yarrelli, p. 418. 

 Goniosoma orgenlinum, C'ost.i, Fna Rerjn. JS'ap., Malatdlterigii 



Abdoniinali, Genere Goniosoma, tab. XXXVI. 

 Argentina decagon, Clarke, Trans., Proc. N. Zcjal. lust., vol. XI 



(1878), p. 295. tab. XIV, fig. infer, (vide lUy, 1. c). 

 (?) Argentina elongata, Htjtto.v, Ann., Mag. Xnt. Hist., ser. ."J, 



vol. Ill, p. 53; Gthr, Dei'p -Veu Fish., fhull. Exped., p. 



218, fab. LV, fig. B. 



Tlie lJcbi'i(hil Siil-Smelt attains at most ahoiit lialf 

 tlie Icngtli (if tlie pi-ecL'ding' s])ecios". It is l)esides, in 

 must cases, of a more i/longated form, the greate.st 

 depth in adult specimens — witli tlie exception of gi-a- 

 \i(l females — heing about l."i % of the length of the 

 body; l)ut in this i-espeet tiiere is no constant distinc- 

 tion''. In other respects too l)oth species are so like 

 each other that the essential differences are but few. 

 The Hebridal Siil-Smelt has a comparatively longer anal 

 fin, a higher dorsal fin, smaller eves and less developed 

 adipose membrane on the head — it is no true deep- 

 sea fish — fewer rays in the pectoral and \entral fins, 

 fewer scales, vertebra;, and gill-rakers, but a somewhat 

 longer peduncle of the tail (behind the adipose and the 

 anal fins). To these we should add a characteristic 

 first remarked by Lill.ieborg, the faint S-shaped cur- 

 vature of the lower posterior margin of the operculum 

 in the Hebridal Siil-Smelt. But in coloration this spe- 

 cies differs widely from the Greater Siil-Smelt, o\\'ing 

 to its thin and more silvery scales, most of them de- 

 ciduous. 



The length of the head in adult specimens is some- 

 what les.s than '/^ of that of the l)ody, the longitudinal 

 diameter of the eyes rather more than ', ,, and the 

 postorbital length about ",'5, of the length of the head. 

 The forehead is flat, the supraorbital parts being hardly 

 at all tumid, but their outer margins indented in a 

 rounded manner above the middle of the eyes. The 

 nostrils lie rather near to the orbits, and they are of 

 fairly equal size, or the anterior is even a little larger 

 than the posterior. They are circular, or oblong in the 

 longitudinal direction of the body. The breadth of the 

 snout at the nostrils is perceptibly less than the width of 

 the interorbital space, and its length is about equal to the 

 longitudinal diameter of the eyes. The jaws are relati- 

 vely somewhat shorter than in the Greater Siil-Smelt, 



the length of the maxillarie.s being about 19%, that of 

 the lower jaw about ?,()'., %, of the length of the head. 

 The tran.sverse row of palatine teeth is sharply defined 

 at both ends, th<! margin of the palatine bones being 

 indented just behind them. The gill-rakers are not 

 only more scattered but also comparativelv shorter 

 than in the preceding species. The pseudobranchia' 

 arc rather large here as there. 



The height of the dorsal tin is about equal to the 

 length of the head reduced, or nearly 18 ?» of the 

 length of the body, and perceptibh- nmre than twice 

 the length of the base of the fin. Here too the anal 

 fin begins at the termination of the third ipiarter of 

 the length af the body, but the length of its l)ase is 

 nearly "/s of tliat of the head. The adipose fin begins 

 above the 2nd or 3rd branched ray in the anal. 



The pectoral fins, the length of which is aliout 

 13 '/g % of that of the body, are rather shorter, the 

 ventrals, on the other hand, somewhat longer, than in 

 the preceding species, the length of the latter being 

 only about \/u, less than that of the former. 



The form of the scales yaries a.s in the preceding 

 species, but their sjiines are less developed. 



In fresh s])ecimens, according to Edward, the 

 body is so transparent that on holding it up to the 

 liglit the \ertebra? can be distinguished. The divisions 

 of the brain are even more distinctly visible through 

 the parietal and frontal bones tlian in the preceding 

 specie.s. The back is of an olive gray, the sides and 

 opercula are silvery, the former, however, according to 

 Edw.vkd, with different shades of coloin- between the 

 several longitudinal ridges. The space between the two 

 ridges nearest to the back is of a deep amber, the 

 next strip greenish blue, the third space, just below 

 the lateral line, silver^' white -with a In-ight metallic 

 lustre; the lower spaces are similar to the upper, but 

 their colours are fainter. The belly is then grayish white, 

 with a dash of greenish blue and purple. The fins are 

 for the most part transparent, the dorsal ])ale gray, the 

 anal white, the caudal of a deeper gray, with "a dark 

 longitudinal mark along either lobe near to its outer 

 edge" (Day). The paired fins are pale, "of a faint rose 

 colour" (MoKEAu). "A black spot on the upper edge 

 of the orliit, and a smaller one on the snout" (L^ay). 



" According to Moeeau (lie ordinary length of tliis species in tlie Mediterranean Sea is 14 — 20 cm. Collett's largest specimen 

 from Norway was 2(i5 mm. long. 



' COLLETT states as a change of growth that, in young specimens (with the Irngtli of the body to the end of the caudal lobes less 

 than 15 cm.), the greatest depth is about '/g, in the oldest specimens (more than 21 cm. long) about '/g, of the said length of the body. 



