262 MR. R. I. POCOCK — MIMICRY IN SPIDERS. 



Some species of the genus Castaneira (e. g., C. temdformis) from Paraguay, 

 which mimics Pacliycondyla, have the carapace very long and marked on each 

 side by a deep groove forming a constriction behind the square cephalic 

 portion. The legs are either spotted or annulated. 



Somewhat similar are the species of Corinomma from the Oriental Region, 

 which have the constricted carapace of the above-mentioned genera, with the 

 integument black, olive, or red in colour and clothed with variously coloured 

 plumose hairs forming transverse segmental zones on the cylindrical abdomen. 

 The genus Psellocoptis contains large and handsome spiders from Venezuela, 

 where they are found running rapidly over the trunks of trees. They are 

 clothed with thick plumose pubescence, forming elegant yellow and white 

 patterns on a black ground. The species of Apocliinomma also closely 

 resemble ants. The integument is generally black and shagreened and 

 clothed with scaly, plumose, or simple white or yellow hairs, forming 

 segmental belts on the abdomen. The carapace is long, rounded or truncated 

 in front and attenuated behind ; the abdomen is sometimes globular, with a 

 long anterior stalk-like prolongation, sometimes cylindrical, with usually a 

 lateral constriction. Sphecotypus niger (fig. 2) differs principally from 

 Apocliinomma in having a deep cephalothoracic constriction. It is a large 

 blackish species common in the forests of tropical America, where it mimics 

 Pachycondyla villosa even more closely than does Castaneira tenuiformis. 



Two striking instances are found amongst the Thomisidse *. Apliantocliilus 

 has the integument horny, granular, and black or brown in colour and 

 shining ; the carapace is squared and round with a spine on each side in 

 front, and is narrowed and pointed behind, with a shallow lateral constriction. 

 The abdomen is oval, marked with transverse integumental folds and studded 

 with transverse rows of pale bristles which simulate segmentation. The palpi 

 are tucked away beneath the edge of the carapace, and the four pairs of legs 

 representing the antennae and legs of the ant are long and slender. During 

 life the species of this genus, which occurs in Venezuela and Brazil, offer a 

 striking resemblance to ants of the genus Cryptocerus. 



Amycicea forticeps (figs. 5-5 a) mimics and lives in company with the little 

 red spinning ant, CEcopJiylla smaragdina, a common Oriental species. The 

 colour of the spider is orange-red, relieved by a pair of black spots at the end 

 of the abdomen. The carapace is high and rounded in front, but narrowed and 

 prolonged behind. The abdomen is very different from that of the typical 

 Thomisidse, being cylindrical and elongated, rounded in front and behind^ 

 with a shallow median constriction, and leaves the carapace uncovered in front. 

 The high and rounded cephalothorax of this spider represents the abdomen 

 of the ant, the waists of the two correspond, and the long, constricted 

 abdomen of the spider with the large black spots at the end, imitate the 



* These two cases of ant-mimicry were detected by Simon, Hist. Nat. Araignees, vol. i. 

 pp. 957 & 988, 1895. 



