SAND-EEL. 



571 



The length tVoiii the tij) of tlie ui>i)cr j;nv to the occi- 

 put is twice the deptli iit tlie occi|iiit, anil in ;i small 

 specimen (about 15 cm. loni;) nearl\- ' ^ of tlie total 

 length (including the whole of the caudal tin). The 

 length of the head — according to the method of mea- 

 suring it usually employed in this work, from the tip 

 of the snout to the hindmost ])oint of the opercular 

 (here the suboj)ercular) flap — measures in specimens 

 between 11 and 14 cm. long about 21 % (20-8— 207 

 %, according to our measurements) of the length of the 

 body (from the tip of the snout to the end of the 

 middle caudal rays), and in specimens between 26 and 

 28 cm. long about 19 % (18'5— 19'6 %) of the same 

 length. The eye is fairly round, but closely surrounded 

 by a sharp, soft orbital margin, the opening of which 

 is usually transversely oblong (the height greater than 

 the length). Both in large and small specimens the 

 hind margin of the eye lies half-wa.}' between the tip 

 of the lower jaw and that of the gill-cover; Ijut in 

 large specimens the size of the eye is less in proportion 

 to that of the bodv than in smaller ones, the diameter 

 of the eye in a specimen 30 cm. long being only twice 

 as great as in a specimen 7' , cm. in length. During 

 the growth of the body from 1 1 to 28 cm. the longi- 

 tudinal diameter of the eje decreases from aljout o' .-, 

 to 1' 4 % of the length of the body or from 16 to 9 Si 

 of the length of the head from the tip of the snout. 

 The length of the snout measures about 60 % (61 'A, — 

 59\'o %) of the postorbital length of the head, or aliout 

 Va (32 '/a— 35 %) of the total length of the head from 

 the tip of the snout, in specimens between 11 and 28 

 cm. long. The breadth of the interorbital space, on 

 the other hand, shows even relative inci'ease during 

 growth, in the said specimens from about 2'/, % to 

 about 3^ 4 % of the length of the body, or from 12' ., 

 to IS'/j % of the length of the head. 



The nostrils are small, oblong, not raised, and only 

 slightlv more than twice as large as the small muci- 

 ferous poi'es which retain their normal position in the 

 supraorbital, suborbital, and preoperculo-mandibular 

 branches of the cephalic system of the lateral line. The 

 anterior nostrils are set on each side somewhat Ijehind 

 the middle point between the eye and the tip of the 

 snout, the posterior somewhat higher l)ut much nearer 

 to the anterior nostrils than to the eye. The tip of the 

 snout, seen from above, is parabolic, flattened, and flex- 

 ible; it projects considerably, almost concealing the upper 

 jaw (the intermaxillaries) when the mouth is closed. 



The mouth is rather large, but capaltle of hardly 

 any protrusion. When the jaws are opened, the njjper 

 jaw thus assumes a vertical position and Ijcnds the tip 

 of the snout upwards. In young specimens, however, 

 the mouth is somewhat protrusile. The intermaxillary 

 bone is rather narrow, and extends somewhat beiund 

 the nostrils when the mouth is closed. The maxillary 

 bone is nnicli more robust; it articulates below the sides 

 of the tip of the snout and, when the mouth is closed, 

 lies hidden under a dermal fold of tlie cheek (the lower 

 pi'eorlntal margin). The total length of the upper jaw, 

 from the tip of the snout to the hind extremity of the 

 maxillary bones, increases with age, in the specimens men- 

 tioned above — between 11 and 28 cm. long — from 6 to 

 eVs % of the length of the body or from 29 to 34 % of that 

 of the he;id. The lower jaw is fairly strong and much 

 longer than the u])per. In the specimens just mentioned 

 its length measures about ^ ,„ (10'2 — 9'1 %) of that of 

 the body or about V2 (46'8 — 50 %) of that of the head, 

 and is greater than the length of the pectoral flns 

 (113 — 155 % thereof). Its articulation lies vertically 

 below the eye, and its tomial margin is deeply sinuated. 

 The conical tip of the lower jaw, which projects beyond 

 the upper jaw, and thus forms the tip of the head, 

 measures as nuich as ' :; — '4 of the snout proper, or 

 even a little more. The lips are well-developed. Trans- 

 verse palatal folds are present both in the upper jaw 

 and in the lower. Teeth are entirely wanting in the 

 jaAvs, on the palatine bones, and on the tongue. On 

 the head of the vomer alone we tind two teeth, which 

 are strong, set close together, and curved. The pha- 

 r}'ngeals, which are small (3 above and 1, elongated in 

 foi'm, below on each side), are furnished with close-set, 

 tine, cardiform teeth. The gill-rakers are setiform, 

 numbering about 25 on the front surface of the first 

 branchial arch. The tongue is of a shape not so com- 

 mon among fishes: it is free, broad but thin, and con- 

 cave at the top, with depressed, rounded tip. 



The gill-openings are large, nearly the whole of 

 the gill-cover being free at the top, M'hile below the 

 opening is continued down to the articulation of the 

 lower jaw. The branchiostegal membrane is thus com- 

 pletely divided, without lieing united to the narrow 

 front part of the belly (the isthmus) between the gills. 

 It is furnished with 7 rays, which are, however, diffi- 

 cult to count, as the outermost ray is rather short and 

 fine, and is hidden by the extraordinarily strong muscles. 

 The rays are covered by the margin of the fold and 



