202 AiirHIPODA NOUMALIA. 



1. Gammaracanthus loricatus. (Plate XXXVI. fig. 2.) B.M. 



Gammarus loricatus, Sabi/ie, Parri/'s First Voyage, Append, p. ccxxxi, 

 pi. 1. f. 7. 



Krinjer, Grnnl. Amjip. p. 22. pi. 1. f. 4. 

 Edwards, Hist, des Crust, iii. p. 52. 



Boss, Appendix to Parn/s Tftird Voi/aije, p. 118; Pohr Voyage, 

 p. 204 ; Appendix to Second Voyage in Search of a N. TV. Pass- 

 age, p. Ixxxix, 1835. 

 Pefl, Belchers Last of the Arctic Voyages, Append, p. 405. 

 MS. in Cat. Hunt. Museian, p. 93. 



Cephalon having a long, carinated, depressed rostrum. Pereion dor- 

 sally carinated, the three posterior segments having the carina 

 produced posteriorly into a tooth ; each segment has the lateral 

 margin externally raised. Pleon dorsaUy carinated, each segment, 

 except the sixth, having the carina posteriorly produced iato a 

 sharp tooth. Eyes imperfectly round. Superior antennae half the 

 length of the animal; peduncle as long as the flageUum, third 

 joint shorter than the preceding, second shorter than the first ; 

 secondary appendage longer than the last joint of the peduncle. 

 Inferior antennae one-third shorter than the superior ; peduncle 

 somewhat longer than the peduncle of the superior. First pair of 

 gnathopoda having the carpus produced to an inferior angle ; pro- 

 podos subovate, broadest at the carpal extremity ; palm longer than 

 the inferior margin, oblique, convex both anteriorly and posteriorly, 

 forming a central depression, into which the dactylos, which is 

 shorter than the palm, impinges : second pair uniform with the 

 first. Coxae gradually increasing in depth to the second pair of 

 pereiopoda. First two pairs of pereiopoda subequal ; thu'd pair 

 of pereiopoda longer than the second, fourth much longer than the 

 third, fifth much shorter than either of the two preceding ; basa 

 of the last thi-ee pairs but slightly dilated. Penultimate pair of 

 pleopoda shorter than the preceding ; posterior pair much longer 

 than either of the two preceding, peduncle not more than half as 

 long as the rami ; rami equal in length, obtusely lanceolate, mar- 

 gins fringed with cOia. Telson consisting of two small, round, 

 foliaceous plates. 



Length I'j inch. 



Hab. Prince Regent's Inlet, abundant (Sir J. C. Boss) ; Arctic Seas 

 (Admiral Parry and Sir Edward Belcher) ; Greenland (Kroyer). 



Sir James Ross, in the Appendix to the ' Second Voyage in Seaich 

 of a JTorth-west Passage,' remarks that "in some specimens the 

 rostnmi is so very minute as hardly to be distinguishable, whilst 

 in others it is very large." The close resemblance which this animal 

 bears to ^Ltylus carinatus, in which the rostrum is much smaller, 

 may have conduced to the bcHef of this apparent variation. 



