THEMISTO BREVISPINOSA. 385 



scale. The third joint of the peduncle of the superior an- 

 tennse 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 not fringed. 

 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 in- 

 ternal branch of the fourth fin is longer than the first joint 

 of the external branch ; and it is both more strongly 

 ringed 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 dart-like point. The 

 external caudal fins end in a sharp point inferiorly, and 

 are rounded inferiorly ; the internal fins are oblong, oval, 

 and pointed at the extremity. These are both fringed 

 at their inferior edges and at their extremities. The late- 

 ral 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 its bifurcation is very acute ; 

 the extremities of the prongs are also sharp-pointed, and 

 of a black colour." 



Amongst the numerous and interesting additions to our 

 knowledge of the smaller Crustacea, for which we are in- 

 debted to Mr. H. D. Goodsir, are the three foregoing 

 species of the family Mysid^. As I have never seen spe- 

 cimens of either of them, I have thought it best to give, 

 verbatim, Mr. Goodsir's own descriptions, although some- 

 what diftuse, with copies of his figures. 



