AHCTIf SriU'ELUS. 



943 



the preceding species, being almost entirely contiguous 

 when the mouth jiiid gill-openings are closed, the only 

 sijiice hetween tlicni then consisting of ;i lanceohitc giij) 

 at the exti-enu' tV(int. just hcliind the s>-nipl)vsis. 



Tlie dentition of tlie mouth iind |)luir\ii.\ is \ve;iker 

 than in the preceding species, otherwise of similar tyjje. 

 The preopei'culuin is vertically set, slightly curved, with 

 the hind uifirgiu cxpnuded hut extremely thin. The 

 operculum, which is half free at the upper raai'gin, is 

 quadrangular with rounded coi'iiers and smaller than 

 the suboperculum, which lies belo\v and inside it; but 

 these bones, as well as the interoperculum, are so thin 

 and so densely covered with large scales that it is difti- 

 cult to determine the limits between them and their 

 shape without damaging the solitary specimen at our 

 disposal. The liranchiostegal membranes, with their 8 

 rays, are united to each other below and in front, but 

 onh' for a very short distance, to a line with the centre 

 of the eyes. The pseudobranchire are distinct and re- 

 gular. The gill-rakers resemble those of the preceding 

 species, and number 1(1 or 17 in the outer row on the 

 first branchial arch. The last branchial arch of this 

 s])ecies too is mostly coalescent with the clavicular arch, 

 the hindmost gill-slit being consequently very small. 



In contradistinction to the preceding species, the 

 Arctic Scopelus belongs to a, subdivision of the geiuis, 

 proposed by GcxTHEii, in which the dorsal fin is shorter 

 than the anal. The former tin begins half-way along 

 tlie bod\' minus the caudal tin, at a distance from the 

 tip of the snout measuring about 51 %" of the length 

 of the body excluding the caudal fin. Its base measures 

 about 15 %' of the same length. Its first three rays 

 are simple; the first two unarticulated. According to 

 Krgyer's figure the fourtli t)r fifth riiy is the longest, 

 the posterior rays uniformly decreasing in length. The 

 adipose fin lies alidut half-way between the dorsal and 

 caudal fins, is broader (longer at the base) than in the 

 preceding species, and is supported by fine fibrils (flex- 

 ible, corneous rods) within it. The anal fin begins at 

 a distance from the tip of the snout measuring about 



" Answering to 4 1 % in the preceding species. 



' Answering to 30 'o in the preceding species. 



' Answering to about 59 °i in the preceding species. 



"' Answering to nbont 22 % in the preceding species. 



' Answering to 7 — 8 % in the preceding species. 



•^ Answering 1o nearly 10 % in the preceding species. 



' In the preceding species about twice this breadth. 



* .\nswering to nearly 13 ;i in the preceding species. 



.\nswering to about 13' ., % in the preceding species. 



Answering to nearly 18 °i in the preceding species. 



Scnn,/;,iOi-/rin Fishes. 



54',., %' of the length of the body excluding the caudal 

 fin, and its length is about 24 %'' of the same. The 

 first two rays are simjile and unarticulated, the first 

 ray being very small. The bi'anched rays, accordingly 

 to Kki)Yki;"s figure, decre.isc uniformly and slowdj' in 

 length behind. The shajie of the caudal fin cannot be 

 ascertained from (jui- specimen; but the fin has certainly 

 been deeply forked, miuI the length of its middle rays, 

 here as well as in the preceding species, differs but 

 little from thi' intei-oi-bital width, being nearly G\/„ %' 

 of the length of the body excluding the caudal fin. In 

 oiu- specimen we find 8 supporting (s|)inous) rays at the 

 upper margin of the caudal fin and fi at the bjwei-. 

 The pectoral fins, which are set obliquely and rather 

 high, are narrow, but very long, measuring 18 %■'' of 

 the length of the body excluding the caudid tin. The 

 ventral fins, which lie rather near each other, the di- 

 stance between them l)eing scarcely equal to the breadth 

 of the base of either fin", are shorter than in the pre- 

 ceding species. Their length is Vio* of that of the body 

 excluding the caudal fin. Their distance from the tip 

 of the snout, here as in the preceding species, is about 

 '/n, of the length of the body excluding the caudal fin. 

 The distance between them and the foremost point of 

 the base of the pectoral fins (the preabdominal length) 

 is '/j', and that between them and the beginning of 

 the anal fin (the postabdominal length) about 15 %\ 

 of the length of the bodj^ excluding the caudal fin. 

 The shortening of the body in this species, as opposed 

 to the preceding one, thus affects in the most essential 

 degree the abdominal region. 



The scales are t'omparativelj^ larger than in the 

 preceding species, but equally thin and of essentially 

 the same shape and texture. The greatest difference 

 meets us in the scales of the lateral line, which are 

 considerably higher (broader). A scale from the middle 

 of the lateral line in our specimen is 2'1 mm. long and 

 5'8 mm. broad. Its anterior (inserted) margin is rather 

 evenly rounded (not triangularly pointed at the middle, 

 as in the jjreceding species), with only faint sinuses, and 



