OAMMAUID.K. 147 



from the former it is distinguished by tlie mandibles being furnished 

 with an appendage, and the telson being entire ; from the hitter in the 

 form of the superior antennfe, a.s also in that of the telson. The separa- 

 tion from Ati/lus may be somewhat arbitrary, but veiy convenient, in 

 consequence of the singular form of the only species known. The name 

 Acanthosoma having been previously nscd for a genus of Coleoptera, 

 I have adopted that projioscd by Bruzelius. I know of this author's 

 work only througli a short notice in the ' American Journal of 

 Science ' for Nov. 1859. It appears to me that he has fallen into 

 the same error that Costa has in Amplutlwnotus. and imited several 

 distinct genera. Pleustesimnoplm, Parampluthoe luistriv, and Fherusa 

 bicusjjis have characters essentially distinct, and it is oidy by giving 

 undue importance to the development of the dorsal teeth that they 

 have been united. 



1. Paramphithoe hystrix. (Plate XXVIII. fig. 1.) B.il. 



Paramphithoe hystrix, liruzrlim, Kotuj. Vet. Akad. Hundl. 1858. 

 Acanthosoma hysti-ix, Oice/i, Appendix to Hoss's Second Vuyayc in 

 Sefireh of a N. Tf'. Passac/e, p. xci. pi. B. f. 4. 



Bell, App. to licle/ter^s JLad of the Arctic Voyages, p. 146. 

 Amphitlioe histrix, Kriiyer, Gron. Amjip. t. xi. f 7. 



Edicdfdti, Hid. des Crust, iii. p. 40. 



Gephalon furnished with avery minute rostnim. First segment of 

 the pereion having a large central dorsal tooth projecting up- 

 wards and forwards on the anterior margin, a small marginal one 

 on each side, and an inferior lateral one near the coxal margin ; 

 on the posterior margin a large central dorsal spine directed u])- 

 wai'ds and backwards, and upon each side a small latei'al one 

 directed backwards ; the six remaining segments of the pereion 

 are each furnished with a very large central dorsal and a largo 

 lateral tooth on each side of the posterior mai'gin, and a lateral 

 central one slightly above the coxal margin. The fii-st two seg- 

 ments of the pleon have upon the posterior margin one central, 

 and upon each side two large lateral teeth, besides the inferior distal 

 angle, which is similarly developed, and a small tooth intermediate 

 between it and the inferior lateral ; the tliird segment carries a 

 large central, and on each side a long lateral tooth, besides the infe- 

 rior dLstal extremity ; the fourth segment carries a minute central 

 and a sublateral spine ; the fifth a sublateral spine only. Ej'cs 

 round, projecting. Superior pair of antenniE haring the first joint of 

 the peduncle longer than the second, and distally armed superiorly 

 with a long spine ; second longer than the third ; third not so long 

 as the first of the flagellum ; fiagellum nearly twice as long as the 

 peduncle. Inferior paii' of anteniuc half as long again as the 

 superior ; third joint of the peduncle armed with a spine upon the 

 inferior and dist{\l extremity, fourth and fifth joints subcqual ; 

 flagellum scarcely longer than the peduncle. Gnathopoda similar in 



f, 2 



