778 MB. B. K. A0STEN ON A. RECENT ZOOLOOIOAL [JunC 16, 



-As has already teen mentioned, the flies belonging to this genus 

 have narrow bodies and long legs, while in many species the front 

 tarsi are white. A medium-sized reddish Oalohata (possibly new), 

 which I found at the Parana de Buyassu, when at rest on a leaf 

 looks exactly like an Ichneumon of the genus Cryptus, holding its 

 fore legs in the air and waving them about just as an Ichneumon 

 waves its antennae. The front tarsi of this species of C'alobata are 

 white, and since all the species of Cryptus have white-banded 

 antennae the resemblance is greatly increased. But as Ichneumons 

 are not armed with stings, while, on the other hand, they attack 

 larvae and not perfect insects, it is difficult to see what benefit the 

 fly can obtain unless the species of Cryptus are distasteful to birds. 



The third instance of protective resemblance belongs to a different 

 category. Among other Dragonflies, Zenithoptera americana, L., 

 a small dark-winged Libelliilid, was not uncommon. At Gurupa, 

 on Fob. 22, 1 noticed that these insects have a habit of settling on 

 the tips of dead twigs from five to ten feet from the ground, and 

 drooping their wings downwards and forwards, so that they look 

 exactly like bunches of dead leaves. Three or four individuals are 

 usually seen on adjacent twigs, and they will remain motionless in 

 this way for several minutes. I am informed by my friend 

 Colonel Bingham, F.Z.S.,that he has observed similar habits in the 

 case of certain species of Dragonflies in India. 



Since my time was fully occupied with the Insects, I cannot say 

 much about the remaining Classes of Arthropods ; nor is it 

 necessary that I should do so, since these groups (Spiders, Scorpions, 

 Myriopods, and Peripatvs) were the special care of Mr. Pickard 

 Cambridge, the results of whose study of the large Hairy Spiders 

 (fam. Therepbosidae) are to be communicated to the Society to-night. 

 These particular Spiders, the monsters of their class, were more 

 or less common at most of the localities visited by us, and Mr. 

 Pickard Cambridge's exertions were rewarded by the acquisition of 

 a large series of specimens, including, I believe, representatives of 

 a number of new species. On landing for the first time on the 

 shores of the Para River after a slight detour rendered necessary by 

 the presence of a dead bullock, attended by the inevitable Urubii 

 Vulture {Cathartes atraius), the first object that met our delighted 

 gaze was one of these Spiders on the stem of a palm-tree. The 

 common species in the vicinity of Para was Avieularia aviculuria, 

 L., of which a specimen was found in almost every palm-stump 

 in a clearing to which we paid several visits. These great spiders 

 rarely leave their retreat during the day, but seem fond of sitting 

 at the mouths of their holes, with the tips of their legs projecting 

 from beneath a protecting layer of thick web. They are very timid, 

 and almost invariably dart back into their holes when approached. 

 In the case of the individuals living in the pahn-stumps, however, 

 a lighted match dropped into the hole was found to be an excellent 

 means of effecting an iramediiite capture. Other species live in 

 leaves, or in bag-webs beneath loose pieces of baik on tree trunks, 

 while in the campo at Sanlarem a new species of TapinaiicJienius 



