SAND-EEL. 
571 
The length from the tip of the upper jaw to the occi- 
put is twice the depth at the occiput, and in a small 
specimen (about 15 cm. long) nearly Vs °f the total 
length (including the whole of the caudal fin). 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 point of the opercular 
(here the subopercular) flap — measures in specimens 
between 11 and 14 cm. long about 21 % (20'8 — 20‘7 
%, 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-way between the tip 
of the lower jaw and that of the gill-cover; but in 
large specimens the size of the eye is less in proportion 
to that of the body 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 V 2 cm. in length. During 
the growth of the body from 11 to 28 cm. the longi- 
tudinal diameter of the eye decreases from about 3 1 / 2 
to l 3 / 4 % of the length of the body or from 16 to 9 % 
of the length of the head from the tip of the snout. 
The length of the snout measures about 60 % (61 V 2 — 
5 9 1 / 2 %) of the postorbital length of the head, or about 
V 3 ( 324 / 2 — 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 increase during 
growth, in the said specimens from about 2 V 2 * to 
about 3 3 / 4 % of the length of the body, or from 1 2 1 / 2 
to I 8 Y 3 % of the length of the head. 
The nostrils are small, oblong, not raised, and only 
slightly more than twice as large as the small muci- 
ferous pores 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 behind 
the middle point between the eye and the tip of the 
snout, the posterior somewhat higher but 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 
jaAV (the intermaxillaries) when the mouth is closed. 
The mouth is rather large, but capable of hardly 
any protrusion. When the jaws are opened, the upper 
jaAv thus assumes a vertical position and bends the tip 
of the snout upwards. In young specimens, however, 
the mouth is someAvhat protrusile. The intermaxillary 
bone is rather narroAv, and extends someAvhat behind 
the nostrils Avhen the mouth is closed. The maxillary 
bone is much more robust; it articulates beloAV the sides 
of the tip of the snout and, Avhen the mouth is closed, 
lies hidden under a dermal fold of the cheek (the lower 
preorbital margin). The total length of the upper jaw, 
from the tip of the snout to the hind extremity of the 
maxillary bones, increases Avith age, in the specimens men- 
tioned above — between 11 and 28 cm. long — from 6 to 
Q 2 / 3 % of the length of the body or from 29 to 34 % of that 
of the head. The loAver jaAV is fairly strong and much 
longer than the upper. In the specimens just mentioned 
its length measures about 7m (10’2- — 9‘1 %) of that of 
the body or about 7a (46*8 — 50 %) of that of the head, 
and is greater than the length of the pectoral fins 
(113 — 155 % thereof). Its articulation lies vertically 
beloAV the eye, and its tomial margin is deeply sinuated. 
The conical tip of the loAver jaAV, Avhich projects beyond 
the upper jaw, and thus forms the tip of the head, 
measures as much as 7 5 — Vi °f the snout proper, or 
even a little more. The lips are Avell-developed. Trans- 
verse palatal folds are present both in the upper jaAV 
and in the lower. Teeth are entirely wanting in the 
jaAvs, on the palatine bones, and on the tongue. O 11 
the head of the vomer alone Ave find two teeth, Avhich 
are strong, set close together, and curved. The pha- 
ryngeals, Avhich are small (3 above and 1, elongated in 
form, beloAV on each side), are furnished Avith close-set, 
fine, 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, Avith depressed, rounded tip. 
The gill-openings are large, nearly the Avhole of 
the gill-cover being free at the top, Avhile beloAV the 
opening is continued doAvn to the articulation of the 
loAver jaAV. The branchiostegal membrane is thus com- 
pletely divided, without being united to the narroAv 
front part of the belly (the isthmus) between the gills. 
It is furnished with 7 rays, which are, hoAvever, 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 
