LERN-EOrODA BIDISCALIS. 201 



Antennules nearly as in Lernxopoda galei. Antenna? 

 very short, stout, and prehensile. The mandibles and 

 other mouth-organs not differing much from those of 

 L. galei. The second maxillipeds very short and 

 stout, each terminating in a very large, fleshy, circular 

 or ear-shaped disk ; the disks united together by a 

 horn-coloured chitinous plug. Colour usually opaque- 

 white, more or less tinged with red, sometimes highly 

 coloured. Length : forehead to the end of the 

 posterior appendages about 7 mm., excluding the 

 appendages, 5'5 mm. 



Male. Though small, proportionally rather larger 

 than the male of Lernxopoda cjalei, but in its general 

 form and in the structure of its appendages having 

 a close resemblance to the male of that species. 



Habitat. Parasitic chiefly on the claspers of male 

 specimens of the tope (or toper), Galeus canis. On 

 topers captured off Valentia, Ireland (cle VismeKane). 

 Firth of Clyde (Mr. Duthie, Fishery Officer). Aber- 

 deen (T. Scott}. Irish Sea (A. Scott). Taken also on 

 the smooth hound. (Mustelus wlgaris) at Polperro, Corn- 

 wall by Mr. W. Laughrin about 1862 (A. M. Norman). 



The dog-fishes on which these parasites were obtained were 

 adult males, and they were usually found adhering on, or 

 near the ends of, the claspers. We have rarely observed 

 them on the claspers of young males. Moreover, as men- 

 tioned by the describer of the species, we almost invariably 

 found that the ends of the claspers on which the parasites 

 occurred were torn and bleeding, but whether the wounds 

 were caused directly by the parasites, or through the efforts 

 made by the fish to throw off its tormentors, was not very 

 clear. Occasionally both claspers had parasites adhering to 

 them. 



The specimens observed by us had usually the front 

 portion of the head of a bright red colour, and sometimes 

 there were blotches of the same colour on other parts of the 

 body; frequently also we found one, and more rarely two, 

 males adhering to the femnle. 



Among the more prominent features by which this Ler- 

 naeopod is distinguished is the comparatively large size of 

 the nearly circular disks which terminate the short second 



