368 



PS\CHE. 



[July, 1902 



Caiiiponotiis Jieixnlcanus Latr. var. p ictus 



For. 

 Formica fusca L. snbpolita Mayr. 

 Lasius nigra. L. 



The collection consisted of 22 species, 



of one of which there was not sufficient 

 material for determination, but apparent- 

 ly it is distinct from any species hitherto 

 found in New England. 



THE SO-CALLED MANDIBLES OF SPIDERS. 



BY WILLIAM A. RILEY, ITHACA, N. Y. 



Regarding the homologies of the first 

 pair of appendages of the arachnids 

 there has always been a question. 

 According to the prevailing view they 

 correspond to the mandibles of insects 

 and are therefore generally referred to 

 as mandibles. The evidence indicates 

 that this application of the term is incor- 

 rect. 



In 1S16 Savigny expressed himself 

 against any attempt to homologize the 

 head appendages of the arachnids with 

 those of insects. He believed that in 

 arachnids the first pair of appendages, 

 commonly known as mandibles, in 

 reality represented a modified pair of 

 legs. 



A little later Latreille, '29, advanced 

 the view that the so-called mandibles 

 are, in fact, the homologues of the sec- 

 ond antennae of Crustacea. He stated 

 that this is evident from a comparison 

 with the second antennae of Crustacea 

 and especially with those of the order 

 Poecilopodes {Limuiiis. ) As indicative 

 of this homology he introduced the 

 term chelicerae, (Gr. chele, claw -H keras, 

 horn), or aiitenncs-finces. 



Following Latreille a number of 

 prominent zoologists have referred to 

 the chelicerae as homologous with the 

 antennae of crustaceans and insects. 

 Thus, Siebold, '48, says " This view of 

 Latreille is the correct one, since the 

 nerves of those organs do not arise from 

 the abdominal ganglia, but directly from 

 the brain, as those of the antennae of 

 Crustacea and Insecta." Ed. Burnett, 

 '54, p. 374. Blackwell, '52, while admit- 

 ting, as highly probable, this homology, 

 proposes as more non-committal the term 

 falces instead of Latreille's term chelicerae. 



While drawing most of their evidence 

 from the Crustacea these authors have 

 uniformly spoken of the appendages in 

 question as corresponding to the anten- 

 nae of insects. Thus, Simon, '92, p. 29, 

 states that the first antennae of Crustacea 

 are not represented in the arachnids 

 and insects but that the second antennae 

 find their homologues in the antennae of 

 insects and the chelicerae of arachnids. 



Those who hold to the view expressed 

 by Simon have fallen into the error of 

 assuming the homology of the antennae 

 of Crustacea and of Hexapoda. But, 



