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



BRACHYURA. 



Tribe O x y r r h y n c H A. 

 Fam. Maiidse. 

 . Genus Hyas, Leach, 1813-1814. 



Hyas araneus (Linn.). 



1758. Cancer araneus, Linn., Systema Naturfe, ed. x. (reprint, 1894), 



p. 628. 

 1790. Cancer bnfo, Herbst, Naturg. Krabben u. Krebse, vol. i. pt 8, 



p. 242, pi. xvii. fig. 95. 

 1814. Hyas araneus, Leach, Edinb. Encycl. vol. vii. p. 431. 

 1816. Hyas aranetts, Leach, Malacostraca Podophth. Britanniae, 



pi. xxi. A. 

 1834. Hyas aranea, Milne-Edward?, Hist. Nat. Crust, vol. i. p. 312. 

 1861. Hi/as araneus, Brandt, Middendorff's Sibirische Reise, vol. ii. 



pt. i. p. 76. 



1863. Hyas araneus, Bell, British Stalk-eyed Crustacea, p. 31, fig. in 

 text. 



1864. Hyas araneus, Goes, Crust, podophth. Suecise &c., in (Efv. Vet.- 

 Akad/Fcirh. p. 161 (extr. p. 1). 



1882. Hyas coarctatus, var., Hoek, Die Crustaceen des Willem 



Barents, in Nied. Arch, fiir Zool., Suppl. vol. i. p. 3, pi. i. fig. 1. 

 1887. Hyas araneus, H. J. Hansen, Dijmphna Krebsdyr, p. 234. 



In regard to this abundant, widely distributed, and well- 

 known species there is still an unsettled question. Leach in 

 one work mentions and in another figures a specimen 

 measuring 16 inches across between the tips of the extended 

 legs. 1 he carapace of the specimen figured is 3^ inches long 

 by a little over 2^ broad. These dimensions, as Leach 

 himself recognizes and as subsequent experience has shown, 

 are very uncommon. From this form, capable of so large a 

 development, the same author in 1815 distinguished, as Hyas 

 coarctatus, a second species, of which a specimen is considered 

 fine when the carapace is 1;^ inch long by | inch wide. Leach 

 did not, however, lay any stress on the difference in size, but 

 on a character less easily appreciable, namely, that the acute 

 lateral postorbital process of the carapace is tuberculate to the 

 rear in Hyas araneus, whereas to the rear in Hyas coarctatus 

 it is much dilated and unarmed. The latter species more- 

 over, in accordance with its name, has the sides of its carapace 

 constricted. It is not said, and it would not be true to say, 

 that they are without constriction in the other form. The 

 fact appears to be that the constriction forms a small pocket 

 (as in the smaller of Leach's two figures of Hyas coarctatus) 

 only in small specimens, but that, as specimens increase in 

 size, it becomes a shallow emargination. 



