877 



towards tlic \fiiti';il iiiariiiii, wliich is iiari'uWL'r, l)iil 

 terete. TIh' ventral |ir(itile in front rnns alnidst jia- 

 rallel to tlu; dorsal, hegimiin^' to rise towards the pe- 

 duncle of the tail at the origin of the anal tin, in the 

 females nnifornilv. bnt in the males with a lii-c^ak 

 caused 1>\' till.' arenate ex|)ansion of the liase of the 

 said tin. 



The shape of the head reminds us most of a threc!- 

 sided pArnniiil, two sides of the pyramid heing formed 

 !)y the cheeks, whit-h apjiroacii each other i)el(_)w, and 

 the third by the fiat forehead antl occiput. Its length, 

 wliich is greatest in the females and the young, varies 

 hetwcen i';5 and IS) % of that of the body, and the 

 length of the head reduced, from the articular kuoljs 

 of the maxillarii'S to the hind margin of the preoper- 

 cnluni, similarly Ijetween 1-V , and V^ % of the length 

 of The body. The horizontal profile of the tip of the 

 snout is broadh' rounded, but its Ijreadth at the arti- 

 culation of the maxillai'ies is considerablv less than in 

 the Smelt, measuring only K! — 20 % (in exceptional 

 cases '1\ %) of the length of the head. The length of 

 the snout, on the other hand, is gi-eater than in the 

 Smelt, being about 33 — 30 % of that of the head. The 

 eyes are also comparatively larger than in the Smelt: 

 in adult Capelins their longitudinal diameter, which is 

 somewhat greater than the vertical, is about 24 — 23 % 

 of the length of the head. The postorbital length of 

 the head is consequently always less in the t'apelin 

 (about 44 — 48 ?4) than half the length of the head, 

 while in the Smelt it is more than half of the same. 

 The forehead is flatter, but its breadth, like that of 

 the snout, is on an average less than in the Smelt, 

 being onlv about 24 — 22 ?>■, of the length of the head, 

 and in exception to the general rule in the family, it 

 is the males that here represent the earlier stages of 

 development. In the opercular apparatus the operculum 

 itself is of the .same shape as that of the Smelt, but 

 the siiuis at the hind margin is indistinct or wanting. 

 The subo|)erculum is somewhat larger than in the Smelt, 

 and more nearly resembles the quadrant of an ellipse. 

 The lower posterior angle of the preoperculum is al- 

 most a right angle. That portion of the margin of the 

 upper jaw which is formed by the intermaxillaries 

 measures onl}- aljout V» — "" 7 (''3 — 74 %) of the longi- 

 tudinal diameter of the eyes; but the length of the 

 maxillaries is about the same as in the Smelt, on an 

 average about 41 %, varying between 38 and 44 %, of 

 that of the head. The length of the lower jaw, on an 



average less than in the Smelt, is about o7 "», \arving 

 bet\\een .")") (exce])tionally .53) and (iO (exce|)tionall\- 

 62) %, of that of the head; but the more essential 

 difference in the shape of the lowei- jaw between these 

 two genei'a is due parth' to the downward (^onvctrgency 

 of the sides of the head in the ('a]ielin, the halves of 

 the htwei' jaw being thus l)rought neai'er to each othei', 

 partly to the less marked cui'vature in an upward di- 

 rection of the point of the lower jaw, which, howev<n', 

 projects, (^ven in the Capelin, beyond the tip of the snout. 

 As regards the distribution of the teeth in the mouth, 

 palate, and pharynx the Capelin in all essential respects 

 resembles the Smelt; but all the teeth of the Capelin 

 are of uniform size and small, about equal in size to 

 the maxillary teeth of the Smelt. On the true hyoid 

 bone (os linfjuaJe or (/lossoliijnle) lies an elliptical row 

 of teeth within the fleshy margins of the tongue, with 

 one or two teeth set inside tlie ellipse, and on each 

 mesopterygoid bone the row of teeth is not situated, 

 as in the Smelt, at the very inner margin, the l)one 

 having grown further inwards to form a more com- 

 plete bottom for the orbit. The gill-rakers resemble 

 those of the Smelt, but are as a rule somewhat more 

 numerous, 35 — 39 on the front of the first branchial 

 arch, and 25 — -30 of these on the lower part of the 

 same. The pseudobranchiiK lie just behind the orbits 

 and above the dermal fold that bounds the |)alate be- 

 hind. They consist of 15 or 16 short lameike, set in 

 an oblique transverse row. The gill-openings are large, 

 extending from about half the upper edge of the oper- 

 culum t(j a line with the anterior margin of the eyes, 

 and the two branchiostegal membranes are entirely free 

 from each other, crossing only to an extremely small 

 extent in front, where the left membrane overlaps the 

 right, but where each is covered by an outer fold of 

 the skin, the right foki lying outside tlie left. The first 

 (lower) four branchiostegal rays are slender and subu- 

 late, the last (upper) 4 — 6 gradually become flatter 

 and broader (sword-shaped) behind (upwards). 



The dorsal flu begins at a distance from the arti- 

 cular knobs of the maxillaries that measures alxjut 50 

 — 55 % of the length of the body, farthest back as a 

 rule in the females. Its base measures about ' j„ (9 

 — 12 %) of the length of the body, and is generally 

 somewhat less (but sometimes, especially in the males, 

 somewhat greater) than its height as expressed by the 

 length of the longest (3rd and 4th, i. e. first branch- 

 ed) rays. When erected, the fin is of an obliquely 



