18/9.] REV. O. P. CAMBRIDGE ON NEW ARANEIDEA. 291 



Gasteracantha observatrix, sp. n. (Plate XXVII. fig. 21.) 



Length of the transverse diameter of an adult female, exclusive of 

 the spines, 4j lines ; length of longitudinal diameter rather more than 

 2£ lines. 



This Spider belongs to the G. mammosa, C. L. Koch, group ; the 

 spines are small, the intermediate and posterior ones being of the same 

 length, and issuing from large circular prominences of the abdomen, 

 which may, however, be really taken to form part of the spine itself. 



The cephalothorax rises to a single undivided, blunt, conical emi- 

 nence on the middle of the caput ; its colour is reddish yellow- 

 brown, darkest on the sides and thorax, and clothed thinly with 

 grey hairs, of which some form a marginal band. 



The legs are dull yellow, marked and irregularly annulated with 

 reddish brown. 



The abdomen is yellow-brown, clothed with grey hairs, and marked 

 and marbled on the upperside with clearer yellow patches of different 

 sizes, forming roughly an anterior curved band and a central large cru- 

 ciform marking. The sigilla are normal in number ( 10 in front and !) 

 behind); but the four centrals of the front row are as large, or nearly 

 so, as any of the rest ; in fact the two fore centrals are the largest of 

 all. Along the central longitudinal line are some small supernume- 

 rary sigilla. 



Examples of this Spider, which is allied to G. roseolimbata, Dol., 

 and G. canningensis, Stol, were received from the Pratos Reef in 

 the China seas, where they were taken by Dr. C. Collingwood, M.D., 

 and kindly sent to me, some years ago. 



Gasteracantha proba, sp. n. (Plate XXVII. fig. 22.) 



This Spider is of a quadrate form, a little narrower behind, and 

 with the posterior outline somewhat curved, and is allied to, but, I 

 think, distinct from, G. cicatrieosa, C. L. Koch. In the adult female 

 tlie length of the longest transverse diameter (which is at the fore 

 margin) is 3| to 4 lines ; longitudinal diameter 2| to 3 lines. 

 The abdominal eminences on which the spines are placed are small. 

 The spines are very small, sharp-conical, and scarcely differ in size ; 

 the anterior ones are placed, one at each extremity of the fore margin 

 (which is but very slightly curved); they are slightly the smallest, 

 and are directed a little forwards ; the intermediate spines are a little 

 directed backwards, and about equally divide the space between the 

 anterior and posterior ones ; but as the hinder division of the abdo- 

 men, on which the latter are placed, is more liable to shrink in preser- 

 vation than the rest, the interval between the intermediate and pos- 

 terior spines is sometimes less than that between the former and the 

 anterior ones. 



The cephalothorax is less raised at the caput than in most other 

 species of the genus ; the caput also, instead of being elevated in the 

 middle, has a longitudinal furrow along that part ; its colour varies 

 from brownish yellow to dark blackish brown ; and it is clothed with 

 short grey hairs. 



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