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



Brandt, in distinguishing the species, uses Leach's character 

 of tuberculation, saying that the part of the carapace in 

 question has about two or three warts in Ilyas araneus and 

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

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

 the meaning seems plain, although the Latinity is not 

 Ciceronian. He adds that in Hyas araneus the breadth of 

 the front third of the carapace is a little less or more than 

 half the extreme breadth, but that in Hyas coarctatus this 

 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 affections of a broad-fronted Juliet, since we, 

 with all appliances and means to boot, can scarcely keep their 

 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 spreading 

 form of the postorbital processes which distinguishes the 

 present species [Hyas coarctatus] in its perfect adult condition, 

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

 Hailstone's Hyas serratus as undoubtedly only a very young 

 form of Hyas coarctatus. 



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

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

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

 of the latter " to be strictly entitled to specific 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 H. coarctatus were young individuals. 

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

 descends into much deeper waters than those frequented 

 by H. araneus. 



Brandt considers the Hyas coarctata of De Kay (Nat. Hist. 

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

 H. 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 doubt 

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

 from Stimpson. That author, he observes, in the Pr. Ac. 

 Philadelphia, 1857, " describes a new species, latifrons, as 

 common in Bering Sea, apparently using the same specimens 

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

 H. latijrons.^ though closely allied to coarctatus, is certainly 



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