423 



the last segment of metasome, in addition to the 2 usual ones, by the much 

 shorter superior antennae, which, moreover, are without any trace of calceolee, 

 and finally,, by the rather different shape of the gnathopoda. 



Occurrence. Some specimens of this form were collected, many years 



ago, in the inner part of the Hardangerfjord, at Utne, from a depth of 300 



-400 fathoms, but were at that time confounded with E. lonyipes. It also 



occurs in the Trondhjemsfjord, where a few specimens were collected, in the 



summer of 1891, likewise from a very considerable depth. 



Gen. 2. Rhachotropis, S. Smith, 1883. 



Syu. : Amphithonotus, Stimpson (part). 

 Tritropis, Boeck. 



Body scarcely at all compressed, and more or less spiny, the posterior 

 part having a distinct dorsal keel, and, on each side of this, a subdorsal 

 one, both generally elevated to acute, posteriorly pointing projections. Cephalon 

 more or less produced in front, and having the lateral corners narrow lingui- 

 form. Coxal plates comparatively small ; 1st pair expanded in front to a 

 narrow lobe stretching along the side of the cephalon; 4th pair not much 

 larger than the preceding pairs, and but very slightly emarginated posteriorly. 

 Epimeral plates of metasome rounded, those of last segment serrated on the 

 hind edge. Eyes more or less distinctly developed. Superior antennae, as a 

 rule, in female shorter than the inferior, and provided with a very small, 

 nodiform, though distinctly biarticulate accessory appendage tipped by a rather 

 fully-developed auditory seta and a few small spines. Both pairs of antennae 

 in male much more elongated than in female. Oral parts nearly of same 

 structure as in Eusirus. Gnathopoda very strongly built and nearly equal, 

 carpus comparatively short, and produced below to a setiferous lobe, its distal 

 part not attenuated, propodos of considerable size and oblong oval in form, 

 with the palm very oblique. Pereiopoda slender and elongated, the 3 posterior 

 pairs rapidly increasing in length, basal joint of last pair more expanded 

 than that of the 2 preceding pairs. Last pair of uropoda with the rami more 

 or less foliaceous in character. Telson comparatively large, and having the 

 outer part deeply cleft. 



Remarks. The genus Amphithonotus of Costa, which is here quoted 

 as a synonym, is a most collective one, including, as it does, forms belonging 

 to several different genera, of -which probably none are referable to the 

 present genus. But Stimpson subsequently referred to it a species, A. 



