459 



emarginated posteriorly in their upper part. Eyes imperfectly developed. 

 Antennae slender and elongated, the superior ones being much the longer, 

 and having no accessory appendage. Buccal area rather projecting. Anterior 

 lip rounded; posterior lip rather large, and without any inner lobes. Mandibles 

 strong, with the cutting part greatly produced and coarsely dentated, secondary 

 lamella present only on the left mandible, molar expansion large and massive. 

 palp of moderate size. First pair of maxillae with the masticatory lobe not 

 very large, basal lobe rather broad, and edged with numerous ciliated setae, 

 palp not at all expanded distally. Second pair of maxillae with both lobes 

 well developed and densely setous at the tip. Maxillipeds not very large, 

 basal lobes of normal appearance, masticatory lobes scarcely as large as the 

 latter, palp comparatively small. Grnathopoda extremely slender, and rather 

 unequal in length, the posterior ones being much the longer, propodos in both 

 pairs extremely narrow, nearly linear in form, with the palm very short and 

 transverse. Pereiopoda slender and elongated, the 3 posterior pairs succes- 

 sively increasing in length, and having the basal joint laminaiiy expanded. 

 The 2 anterior pairs of uropoda of normal structure; last pair having the 

 basal part quite short, and the rami rather unequal, the inner one being much 

 the larger, both mucroniform in shape, and edged with small spinules. Telsou 

 comparatively broad, and somewhat navicular in shape, the upper face being 

 hollowed, and the lower face keeled longitudinally. 



Remarks. The present new genus is founded upon the form described 

 by Boeck as AmpMilwpsis longimana. It is obvious that this form cannot 

 properly be regarded as congeneric with Ampliitliopsis longicaudata of the same 

 author, and, as it moreover, differs in some points very markedly, from 

 the other known genera, I have felt justified in regarding it as the type of a 

 distinct genus. The generic name here proposed refers to the extremely 

 slender form of the gnathopoda. In the structure of the telson and the last 

 pair of uropoda, the genus strongly resembles the ParawpMthoida, and perhaps 

 both this and the preceding genus, should, in spite of the non-bilobular 

 anterior lip, be more properly referred to that family than to the Cattiopiidce. 

 The genus comprises as yet but a single species, to be described below. 



13. Leptamphopus longimanus (Boeck). 



(PL 162) 

 Am2)hitho2)sis longimana, Boeck, Crust, amph. bor. & arct. p. 120. 



Body slender and elongated, with the back evenly rounded throughout. 

 Cephalon about the length of the first 2 segments of mesosome combined, 



