994 



SCAXDINAVIAX FISnES. 



margin shows an arcuate indentation. Obliquel)' across 

 its surface, from the articular head to the lower pos- 

 terior corner, runs a groove, in front of which the 

 lower anterior, triangular part of its surface is some- 

 what tumid, but smooth. The suboperculum has a 

 rounded triangular form, with the hind margin sharply 

 curved. The length of its upper margin, which coincides 

 with the breadth of the operculum, is about 10 — 12 % 

 of the length of the head. The interoperculum is of 

 about the same shape as the subo|ierculum, but much 

 smaller. All the opercular bones are very thin. The 

 branchiostegal membranes are narrow, hardly perceptible 

 at the hind margins of the operculum and suboperculum. 

 In front (below) they follow the branches of the lower 

 jaw, their bi-eadth being but slightly greater than that 

 of these bones or, at the extreme front, less. The 

 branchiostegal rays are also comparatively short, gradu- 

 ally increasing behind (^vitll the exception of the last 

 one) in length and breadth. The anterior are subulate 

 and curved, the posterior of more and more uniform 

 breadth and sabre-shaped, with obliquely set, terete shaft; 



Fig. 251. 



Composite scale from the left side of (he inferior caudal 

 lobe in an Anchovy 16 cm. long. X 3. 



but the hindmost is of a rounded triangular shape, re- 

 sembling in form and position a lower suboperculum. 

 The nine middle rays are set on the ceratohyoid Ijone, 

 the last two on the epihyoid. 



The distance between the dorsal fin and tlie tip of 

 the snout is about 44 (44V2) — 48 %, its height as well 

 as its base about 10 — 11 %, of the length of the body. 

 The first ray is extremely small, the second about Vs as 

 long as the third (the last simple ray), which is slightly 

 shorter than the first branched ray. The last ray in 

 the fin is scarcely elongated. The distance between the 

 anal fin and the tip of the snout is about 60 — 63 '/o %, its 

 base about 14 %, and its lieiglit (tlie lengtli of tlie first 

 branched ray) about 6' ., — 7 %, of the length of the 

 body. It is thus both longer and lower tliaii tlie dorsal 

 fin, and has a more concave outer margin, the last ray 

 being somewhat elongated. The first of the two simple 

 rays at the beginning of the fin is hardly '/s as long 

 as the second, which is almost equal in length to the 

 first branched ray. The caudal fin is deeplj' forked, 

 the length of the middle rays (about 5 — h^!^ % of the 

 length of the body) being even less than '/g of that of 



the longest ones (in the inferior lobe). On each side 

 of the fin are set, as in the Clupeoid forms iramediHtely 

 preceding the Anchovy, a pair of so-called comijosite 

 scales — much smaller, however, than the largest body- 

 scales — one on the superior lobe, the other on the in- 

 ferior, and each consisting of a scalpel-shaped dermal 

 flap, with diamond-like reticulation, and covered with 

 a considerable number (20 — 25) of small scales. These 

 are set in imbricated rows, and each of them is marked 

 with a row of brownish l)lack pigment-spots (fig. 251). 

 The pectoral fins are comparatively short, their 

 length being about equal to the height of the dorsal fin 

 or a little greater, and are obliquely truncate, their shape 

 reminding us strongly of the pectoral fins in those An- 

 chovies where the first ray of these fins shows a fila- 

 mentous elongation. The ventral fins are also obliquely 

 truncate, but much shorter than the pectoral, their length 

 being only about T'/j — 7 % of that of the l)ody. The 

 position of the ventral fins is such that the distance be- 

 tween them and the tip of the snout measures about 



'^m 



Fig. 252. A scale from the left side of an Anchovy 16 cm. long. 

 Three times the natural size. 



40—44 % of the length of the body, or 90—92 % of 

 that between the dorsal fin and the same point. The 

 pi'eabdominal length is about 18 — 22 %, and the post- 

 abdominal about 20 %, of the length of the body. 



The scales are extremely thin and transparent, ra- 

 ther large, but short, and of a quadrangular shape, 

 rounded at the corners (fig. 252). Their posterior (free) 

 part is as large as the anterior (covered) portion, and 

 is also finely striated, the concentric stria; being even 

 twice as numerous as on the latter. The radiating 

 grooves are sharply defined, originating both at tlie an- 

 terior margin and the posterior. The scales of tlie pec- 

 toral fins, and the pointed axillai" scales of the vontral 

 fins are long, extending respectively ^/j and ^4 "^ t'^*^ 

 distance along the fins. The basal scales of the dorsal 

 and anal fins are about tlie same as in the Shads. The 

 median line of the belly is covered, it is true, with 

 ordinary scales; but vestiges of the spiniferous scales 

 that appear in the preceding Clupeoid forms may some- 

 times be found. These take the shape of linear thicken- 



