382 NATURAL ARRANGEMENT OF INSECTS. 



Ptilota. From these loose generalities, we must proceed 

 to the distribution. 



(343. ) It will be of little moment that we invert the 

 order of affinities, as by it we shall save ourselves from 

 the inconsequence of treating the least typical first. 

 Thus, they are divided into the pulmonary Arachnidce, 

 and the tracheal ArachmdcB ; the latter, of course, most 

 closely allied to the hexapod Insecta, although the 

 smaller division. The pulmonary Arachnidce are the 

 most typical, and the most abundant : these are further 

 divided into — 1. AraneidcBj 2. Phryne>dce ; and, 3. the 

 ScorpionidcB. The traclieal Arachnidce comprise — 4. the 

 SolpugidcB ; 5. Phalangidce ; and, 6. the Acaridce. Of 

 the first, the AraneidcB, we have a further division into 

 terrestrial and aquatic. The former inhabit the earth, 

 and are either suspended in the air, or cavities in rocks 

 or trees, or they are affixed to plants, or else they oc- 

 cupy holes in the ground ; whereas the aquatic Araneidct 

 dwell in the midst of the water, in a cell filled with air. 

 The former are divided into Theraphoses and Arachnce 

 proper. In the Theraphoses, the mandibles are articu- 

 lated horizontally, having a vertical, motion ; and, in the 

 Arachnce, they are articulated either vertically, or upon 

 an inclined plane, and have a lateral motion. In the 

 former group of Theraphoses, we find the large and 

 powerful Mygale, the most robust insects of the order. 

 The fact has been doubted, of these catching birds in 

 their nets, and feeding upon them ; but the probability 

 of this has been substantiated and confirmed by a com- 

 munication we have recently received from W. S. 

 MacLeay, Esq., who informs us, that in the vicinity of 

 Sydney, N. S. V>^., he has met with a true bird-catching 

 spider, — having himself found one of the Epeiridce 

 actually devouring the young of a Gusterops, that had, 

 no doubt, lately fiown from the nest; and which is 

 not a solitary instance, as his father, A. MacLeay, Esq., 

 had previously observed a similar fact. He therefore 

 retracts his observations upon Mygale in the Zoo- 

 logical Transactions ; for here, evidently, is a spider 



