346 



SCANDINAVIAN FISHKS. 



fold, black at the margin, which strongly reminds us 

 of the corresponding growth in the true HemlrampM'' . 

 Here this fold disappears during growth, though in 

 specimens 60 ram. long it is still present, but stunted. 

 The following changes in the sha]K> of the snout and 

 the length of the lower ja^v are represented in the 

 figures. In specimens about 60 mm. long the head is 

 roughly of the shape shown in fig. / in the woodcut. 

 It still res(!mbles that of Hemiramplim: the front angle 

 of the snout has passed from obtuse to right and fi- 

 nally to acute; but the tip of the snout is now marked 

 off from the sides by a little sinus on each side: this 



Fig. 92. Posterabryonic changes of g'owth in tlie heads of Scombre- 

 so.v and Ramphistomri. .\fter LOtken. Figs, a — h of Scombresox 

 satti'us; a — e of Rampliistoma beloiie. a magn. 3 diam.; b '/j more 

 tlian tlie natural size; c and d '/i mfre than the natnral size; e '/j 

 more than the natural size. / '/g less than the natural size; g '/j 

 less than the natnral size; h ';,, less than the natural size, a — d 

 mngn. ; £ '/^ less than the natural size. For further explanation 



see the test. 



is the beginning of the elongation of the upper jaw, 

 and while this proceeds, teeth appear in that part of 

 the lower jaw that corresponds to the upper. In spe- 

 cimens about 70 mm. long the head is of the shape 

 shown in fig. ')' in the woodcut; and in specimens about 

 150 mm. long tlie snout has assumed the shape typical 

 of the Garpikes, though the upper jaw is still con- 

 siderably (about three times the diameter of the eye) 



shorter than the lower. In full-grown Garpikes the 

 difference iii tlie length of the jaws is only ecjual to 

 or Va IfiS''' tlian the diameter of the eye. 



The development of the fins presents the usual 

 changes, but interests us by a characteristic peculiarity, 

 the persistency of a part of the embryonic (larval) ver- 

 tical fin and the late appearance of the ventral fins. 

 Even in a young Garpike 15 mm. long this vertical 

 fin is still present at the lower caudal margin, between 

 the anal and caudal fins: between the dorsal and caudal 

 fins it has disap]ieared; but at the ventral margin, from 

 the vent to the end of the first third of the length of 

 the abdomen, a great pai't of it, measuring more than 

 half the depth of the body at this point, is still per- 

 sistent. As yet only the caudal fin, whicii is of a 

 rounded shape, contains distinct rays. In the anal fin, 

 the anterior part of the dorsal fin and tlie upper part 

 of the pectoral fins, which are lobate (furnished with 

 a semi-elliptical basal part) and round, more or less 

 distinct rudiments of the true rays now begin to form; 

 but the remainder of each of these fins is supported 

 by the primary fibrill;i3 alone. Not a trace of the 

 ventral fins is externally visible, with the exception of 

 a light, round spot on each side of the base of the 

 vertical abdominal fin, the distance between it and the 

 vent being scarcely ^/g of the length of this fin. This 

 s])ot forms a scarcely perceptible contrast to the rest 

 of the surface of the body, which is thickly strewn 

 with blackish green collections of pigment*. At these 

 points the ventral fins appear first in the form of small 

 protuberances, which assume a lobate form. But, even 

 in specimens 257-. mm. long — w^here the vei'tical ab- 

 dominal fin is still almost unchanged, and the pigmental 

 spots on the body still present — the ventral fins appear 

 almost as microscopical lobes. In specimens 53 mm. 

 long distinct traces of the vertical abdominal fin are 

 still pi'escnt, but the pigmental spots on the belly and 

 the lower part of the sides have begun to disperse, 

 and to give place to tlie incipient silvery lustre. The 

 ventral fins are even now scarcely more than Iialf a 

 millimetre long, while the length of the pectoral fins 

 is fully 3 mm. or exactly equal to the postorbital 

 length of the head. 



" See Bi.KEKER, Atl. Ichth. lad. Neerl., pp. 53 etc., tab. Scombres. IV, VI — VIII. 



On the upper part of the body these spots are set in fairly regular longitudinal and fiblique transverse rows, the former being 

 especially distinct at the middle of the back. On the lower part of tlie liody they are irregularly arranged in longitudinal rows, and they 

 are wanting only on the under surface of the head and of the front pari of the belly, as well as on the opercnia. 



