29 



oped, Inarticulate, rarely quite rudimentary; 2nd pair with tin- lamella- 

 more or less elongated. Maxillipeds large, with the masticatory Lobes 

 generally largely developed and laminar, hasal lobes much smaller and close 

 together, palp elongated, 4-articnlate. Anterior gnathopoda more or less 

 prehensile, generally not very strong, hut sometimes Largely developed and 

 subehelate ; posterior ones always very feeble and slender, higlilv llexihle and 

 furnished with dense tufts of tactile hairs, dactylus as a rule quite rudimentary. 

 The 3 posterior pairs of pereiopoda successively increasing in length and 

 having the hasal joint laminar. Branchial lamelhe large, sometimes folded 

 transversally on the one or both sides. Incubatory lamelhe edged l>v slender 

 setap. Pleopoda rather powerful. Uropoda with the rami more or less Lanceo- 

 late, last pair well developed, biramous, generally unlike the preeeding j, : ,j rs 

 and having the outer ramus biarticulate. Telsou flattened, entire or more or 

 less deeply cleft, 



Remark*. The Lysianassidse form a very natural subdivision of 



the more typical Amphipoda, and in my opinion ought to be classed as a 

 family equally distinct as the OrchestiidtP. Boeck, however, did nol reg;ml 

 this group as merely a sub-family of the family (ifinnn<iri(^r. In the general 

 habitus the numerous forms comprised in this familv exhibit a rather uni- 

 form appearance, and it is not very long since they were all referred 

 to a single genus, Lysianassa. It is the merit of the late Dr. A. I>oeek. bv 

 a closer examination of the oral parts in the different forms, to have 

 pointed out certain distinctive characters apparently of generic value. By reason 

 of these characters he found himself able to subdivide the earlier genus LiiKi<nit<xxn 

 or Anony.r into a great number of separate new genera, and, although some of 

 the latter have not been sufficiently well characterised, the greater parl of 

 them must, in my opinion, evidently be supported. The family would seem 

 to be chiefly characteristic to northern latitudes, and in the arctic seas some 

 of the species occur in quite an astonishing abundance, having a great im- 

 portance in cleansing the bottom by devouring the carcasses of the several 

 great mammals, such as whales and seals, which are found there. 



Gen. 1. TrischizOStoma, Boeck, ISI',0. 



Body moderately compressed, with the back broadly rounded. < Vpha- 

 lon produced anteriorly over the base of the superior antenna', lateral angles 



not projecting. Second pair of coxal plates much large)' than tl ther and 



greatly dilated interiorly. Epimeral plates ofmetas e large, rounded. Kyes 



very large, occupying the greater part of the sides of the cephalon. Superior 



5 Crustacea, 



