Rev. T. R. R. Stebbing on Arctic Crustacea. 3 



Bratult, ill distinguishing the species, uses Leach's character 

 of tubercuhition, saying that the part of the carapace in 

 question lias about two or three warts in Ilijna aranpiis and 

 only about one or none in Ilyas coarctatus. His words are 

 " subternis vel subbinis " and " subunicavel nulla," of which 

 the meaning seems plain, although the Latinity is not 

 Ciceronian, fie adds that in Ili/as araneus the breadth of 

 the front third of the cara]iace is a little less or more than 

 lialf the extreme breadth, but that in ////as coarctatus tliis 

 front third has more than three fourths, or about four fifths, 

 of the extreme breadth. The two species live in the same 

 waters, so that, when it comes to determining matrimonial 

 alliances, one cannot help wondering how they manage 

 without compasses to prevent a narrow-fronted Romeo from 

 winning the allections of a broad-fronted Juliet, since we, 

 with all ai)pliances and means to boot, can scarcely keep tiieir 

 rival clans from mixing. According to Bell, " In the young 

 state it is very difficult to distinguish the two species, as the 

 former [Hyas araneus^ has, in its early age, the s|>reading 

 form of the postorbilal processes wiiich distinguishes the 

 present species \_lhjas coarctatus] in its perfect adult condition, 

 and which is gradually lost by the other." Bell dismisses 

 Hailstone's Ilyas serralus as undoubtedly only a very young 

 form of IJyas coarctatus. 



Sars, in the ' Crustacea of the Norwegian North-Atlantic 

 Expedition ' (Crust, pt. 2, p. 2, 1886), records both If. araneus 

 and U. coarctatus, and, further, considers Brandt's var. alutacea 

 of the latter " to be strictly entitled to Sj)ecilic distinction." 

 Unfortunately he does not give the characters to be relied on 

 for keeping the three forms apart. Most of the specimens 

 assigned by him to //. coarctatus were young individuals. 

 He notices, as earlier authors had done, that this tbrm 

 descends into much deeper waters than those frequented 

 by //. araneus. 



Brandt coii.<iders the II>/as coarctata of De Kay (Nat. Hist, 

 of New York, 1843) to be a form intermediate between 

 II. araneus and //. coarctatus. Professor S. I. Smith, in 

 ' The Stalk-eyed Crustaceans of the Atlantic Coast of North 

 America north of Cape Cod,' 1879, not only shows no d >ubt 

 of the distinctness of these two sjiccies, but accepts a third 

 from Stimj)son. That author, he observes, in the Pr. Ac. 

 I'hiladelphia, 1857, "describes a new species, latifronsj as 

 common in Bering Sea, apparently using the same specimens 

 which were a few months before referred to //. coarctatus. 

 11. (atijrons.y though closely allied to coarctatus, is certainly 



i* 



