1148 



SCANDINAVIAN FIvSHES. 



mouth, being separated from each other and covered 

 within by a sometimes continuous nasal valvule. The 

 mouth too of some forms is set very far forward, close 

 to the tip of the snout, and fringed with dermal flaps. 

 None of these Sharks gives birth, so far as is known, 

 to living young. 



Within the Scandinavian fauna three species have 

 been observed, belonging to two very similar genera: 



A: Dorsal margin along the beginning of 



the caudal fin armed with spines Fristiurus catulus. 



B: Dorsal margin without special spiny 

 armatuie. 



a: Inner posterior corners of the ven- 

 tral fins acutely prolongated, in the 



males coalescent with each other.. Scylliorhiims canicula. 

 h: Inner posterior corners of the ven- 

 tral fins obtuse, in the males se- 

 parated from each other Scylliorliinus stellaris. 



Obs. De Filippi and Verani" have described from tlie Mediter- 

 raneaQ a Scyllium acanthonotuvi, distinguished by a row of spines ou 

 eacb side of the back, extending from the middle of the head nearly 

 to tlie end of tlie first dorsal fin.- Of the species, however, they had 

 seen only a young individual with vitelline capsule attached. GOn- 

 theh' was of the opinion that this young specimen belonged to one 

 of the above-mentioned jSci/ltiorhini ; GlGLlOLl" referred it to Pristiu- 

 riis. Tht correct explanation may be left to the future; but it seems 

 likely that the spin}' armature is a character of youth which dis- 

 appears entirely in Sc7/llioi-/iinus, partially in Pristiurus. 



Genus PRISTIURUS''. 



Nostrils so remote from each other and from the mouth that the distance between their inner angles is perceptibly 

 greater than that between either of them and the mouth, somewhat greater than their length, and about equal to 

 the distance between their outer angles and the orbital margin. Distance between, the mouth and the tip of the 

 snout greater than the postorbital length of the head {to the frsf brancliiul aperture). Anterior part of the upper 

 caudal margin (tig. 333, a) armed on each side u-itli a row of retral serrated spines. 



This genus contains only one species, which is 

 more nearly appro.ximated by the situation and deli- 



Fig. 333. Egg-capsule of the Black-mouthed Dog-fish (Pristiurus ca- 

 tulus) from the fishing-bank of Jaderen. Nat. size, a, a part of the 

 upper edge of the caudal fin in a Black-mouthed Dog-fish 67 cm. long, 

 superior aspect, X 5 to show the serrated spines and the scale-rows 

 on the dorsal margin between them. 



mitation of the nostrils to the preceding genus than is 

 the case with the succeeding one. It also has a more 

 finely shagreened skin than Scglliorhiniis. In these Sharks, 

 as we have seen in numerous Teleosts, e. g. the Gobies 

 and Salmons, the scales of the tail are larger than those 

 on the anterior part of the trunk. Here we also find 

 that the plaeoid scales of the tail approach more and 

 more to the form of the jaw-teeth, least so, however, 

 in Pristiurus. Besides the above-mentioned characters 

 this genus displays the peculiarity that the tip of the 

 tail is bent downwards, ^vhereas in the following genus 

 it is straighter. The egg-capsules of Pristiurus (fig. 

 333) are distinguished by the absence of horns at the 

 extremity directed backwards in the uterus, which end 

 is rounded by the incurvature of the corners and in- 

 cised at the tip, while the liorns at the other end, 

 one at each corner, are as short as in tJie egg-shells 

 of the Raj's. 



" Mem. R. Accad. Sc. Torino, ser. 2, tom. XVIIl (1809), p. 193, tab., fig 



* Cat. Brit. Mus., Fish., vol. VIII, p. 403. 



' Espos. Intern. Pesca Berlin 1880, Sez. Ital., p. 112. 



^ BoNAP., Fna Ital., Pesci. Established as a subgenus of .':ici/llium. 



