17b Mr Henry Goodsir on a New Q-enu4y 



Long., 1 inch.— -i^a6., Frith of Forth. 

 Description. — The whole body more robust than that of the last described 

 species, and of an opaque white colour, with a single row of black 

 spots along the dorsal mesial line of the abdominal segments. The 

 lirst joint of the peduncle of the inferior antennae ver}'^ short and almost 

 circular ; the two following are slender. The scale which arises from 

 the superior part of the fust joint above the true antennae is very strong 

 at the base, and then tapers gradually to a fine point. A fringe of long 

 hairs borders its inferior edge. These hairs are matted at the extremity 

 so as to give them the appearance of a second joint ; two or three short 

 strong spines arise from the extremity of the scale. The third joint of 

 the peduncle of the superior antennae is considerably produced at its 

 superior angle. The scale which arises beneath the setaceous portions 

 is strong, bent upwards at its extremity, and pointed, but it is not 

 IHnged. The eyes are large ; the reticulated portion circular. The 

 rostrum is of considerable length, but it is not sharp. The internal 

 branch of the third subabdominal fin is minute ; the external one is 

 long, slender, and finely pointed ; it is also fringed with very long 

 hairs. The internal branch of the fourth fin is longer than the first 

 joint of the external branch ; and it is both more strongly fringed and 

 more moveable than that of the last described species. The external 

 branch extends a little beyond the base of the caudal fins. The sixth, 

 or last joint of this branch, suddenly contracts near the extremity to 

 about half its original thickness, ending in a d'irt-like point. The ex- 

 ternal caudal fins end in a sharp point superiorly, and are rounded in- 

 feriorly ; the internal fins are oblong, oval, and pointed at the extrem- 

 ity. These are both fringed at their inferior edges and at their ex- 

 tremities. The lateral edges of the middle plate armed with a single 

 row of strong hooked spines. It is contracted near the base, and the 

 angle formed by the bifurcation is very acute ; the extremities of the 

 prongs are also sharp pointed and of a black colour. 



SECTION II. 



On thr developement of the Ova, and ovi the metamorphoi>eJ( of 

 Caligus. 



The larva of Caligiis bears a great resemblance in its ex- 

 ternal appearance to the larva of Ci/clops on the one hand, 

 and that of Lernea on the other. 



As it is my intention to describe how the ovum escapes from 

 the oviduct, it will be necessary, to understand this properly, to 

 give, in the first place, a short description of the organs of re- 

 production in the female Caligus. 



These ecgisist of the ovaries, int^rjoal and external oviduets,^ 



