350 Mr. J. Blackwall on a new Genus of Araneidea 



single annulus at its extremity ; the fourth pair is the longest, 

 then the first, and the third pair is the shortest ; the tarsi are 

 terminated by claws of the usual number and structure. The 

 palpi are short, somewhat darker-coloured than the legs, and 

 have a curved, pectinated claw al their extremity. The abdomen 

 is nearly circular, rather broader than long, without spines, 

 glossy, moderately convex above, and projects greatly over the 

 base of the cephalothorax; it is of a yellow colour, with five 

 depressed brownish-black spots, forming, near the frontal mar- 

 gin, a transverse curved row whose convexity is directed back- 

 wards, the two exterior spots being the smallest of the five ; 

 four similar spots occur on each side, parallel to the margin ; 

 four smaller ones form a transverse, slightly curved row near 

 the posterior margin, whose convexity is directed forwards ; and 

 there are three similar spots on each side of the medial line, 

 those constituting the intermediate pair being the largest and 

 widest apart ; the under part is much corrugated, and has a 

 large, triangular, dark-brown mark in the middle, comprising 

 within its vertex the spinners, which are encircled by a rim ; 

 the whole is encompassed by a broad yellow margin marked 

 with depressed brownish-black spots, from which lines of the 

 same hue pass towards the centre ; the sexual organs are mo- 

 derately developed, with a small, oval, brownish-yellow process 

 in connexion with their anterior margin, and are of a dark-brown 

 hue, tinged with red, that of the branchial opercula being 

 yellow. 



I have conferred upon this species the name of Horace Waller, 

 Esq., an ardent naturalist, an J the friend and fellow-traveller of 

 Mr. Thornton. 



Eurysoma Walleri bears a strong resemblance to the Gaste- 

 racantha hemispharica of M. Koch (Die Arachniden, Band xi. 

 p. 49, tab. 373. fig. 874), but differs from it in the number, 

 distribution, and relative size of the depressed brownish-black 

 spots on the abdomen, and also in some other particulars. The 

 generic name Gasteracantha being quite inapplicable to a spider 

 absolutely devoid of spines, I have placed this species, notwith- 

 standing the numerous depressed dark-coloured spots with 

 which its carapace is marked, in the genus Eurysoma, to which, 

 for the same reason, I think it would be expedient to transfer 

 Gasteracantha hemispharica. 



Genus Pycnacantha, Blackw. 



Eyes small, disposed on the anterior part of the cephalo- 

 thorax ; the four intermediate ones are seated on a narrow, pro- 

 minent protuberance directed obliquely upwards and forwards, 

 and nearly describe a square; the two superior ones are placed 



