32 Fisherij Board for Scotland. 



not so deep a fish as Marinus. The hump on the dorsal edge, in front 

 of the fin, is a prominent cliarac-ter in Marinus, wliile it is absent in 

 Dactylopterus. The orbit of the former is I'ound ; that of the latter is 

 oval. The orbit of Marinns is the larger. 



The pectoral fin forms an important distinguishing feature. The 

 upper part is cut square across in Dactylopterus, -while in Marinus the 

 distal border is oval. The lower rays in the former fish are thick and 

 much separated from one another ; in the other species the lower rays, 

 although they are thicker than the upper rays, are not so fleshy as 

 those of Dactjdopterus, and only their tips are free. 



The lower jaw in Dactylopterus is not so prominent as in Marinus ; 

 the maxilla, although large in both species, is the bigger in the 

 former. 



The lateral line differs slight!}^ in the two species. In Marinus it 

 forms a more extended curve in its anterior half; in Dactylopterus it 

 begins to descend immediateh^ behind the operculum. 



When the head is viewed from above an approach to the broad head 

 of Cottus and Scorpaena is seen in Dactjdopterus (e.g., Fig. 114); in 

 Marinus the head is narrower (Fig. 115). The interorbital region of 

 the former is hollowed out, while it is flattened in the latter. 



Well-marked differences occur in the numbers of the fin-rays {vide 

 pp. 19 and 30). The membrane between the last ray of the dorsal aiid 

 anal fins and the edge of the body is more extensive in Dactylopterus 

 than in marinus. The colour of the inside of the moiTth forms an 

 important distinguishing feature. In Marinus it is white or pink ; in 

 Dactjdopterus the pharj^nx is black or blue. The two species exhibit 

 intermediate conditions between the forms Perca and Scorpeena. At 

 one end of the series Perca is closely resembled b}' Sehastes marinus, 

 while Sehastes dacti/lopterus shows in its general form and external 

 features a near approach to Sebastes on one hand, and on the other 

 indicates, in respect to its head, a tendency towards the form of 

 Scorpsena {e.g., Forcus). The classification of these fishes is not satis- 

 factory. But any alteration demands a study of all the allied 

 fishes. 



The Ueproductive Organs. 



The male has a large muscular external urogenital papilla (pa., Figs. 

 106 and 112). There are upon it two crater-like orifices, the anterior 

 of which is the opening of the vas deferens, while the posterior one is 

 the aperture of the urethra. 



In the female there is sometimes a small urinary papilla (ur. pap.. 

 Fig. 111). The external aperture of the oviduct is wide {ovd.). It 

 lies between the anus and the urinary papilla. The hind edge of the 

 anus is expanded into a crescent-shaped lij) which lies over the vulva 

 (fr., Fig. 110). The flap varies in shape and size (Fig. 110, A and B). 

 The hind lip of the vulva is sometimes prominent also. The urethra 

 opens to the exterior a little below the apex of the papilla, and on its 

 anterior side. 



The Urinary Bladder. — Male — The urinarj^ bladder was small and 

 jet black on the outside. It was sometimes empty ; but in one or 

 two cases it contained a clear fluid like water. In lies on the right 

 side of the black mesenterj^ that supports the vas deferens and the 

 ureter to the roof of the abdominal cavity. The ureter is median. 



