190 PROCEEDINGS OF THE NATIONAL MUSEUM vol. ni 



extensive systematic use of some sclerites lying just posterior or 

 posteromedial to the second maxillary coxosternites. By Ribaut. 

 Broelemann, Attems, and others they have been termed the maxillary 

 pleurites. Their shape, position, and degree of development and 

 their presence or absence have distinct systematic significance. They 

 seem to represent, at least in part, variously sclerotized portions of 

 the membrane that connects the maxillae \vith the prehensorial seg- 

 ment lying to the rear. They are probably not parts of the primitive 

 second maxillae at all, though there is evidence in some genera, e.g., 

 Arctogeophilus and probably some geophilines, that they have been 

 incorporated secondarily into the definitive second maxillary coxo- 

 sternites. Since their basic morphological identity is unclear, and 

 since in any event the evidence suggests they are not entirely or 

 possibly not at all pleural in origin, it seems preferable to apply to 

 them some other, simply descriptive term — one without morphological 

 implications or inferences of homology. For this reason I propose 

 that they be called postmaxillary sclerites. 



Note C, Prehensorial Poison Apparatus: Apparently the first 

 person to recognize the sclerotized poison calyx as a valuable diag- 

 nostic adjunct was Verhoeff, who utilized it in several studies of the 

 genus Strigamia (Scolioplanes, and Linotaenia of authors). The shape 

 and position of the calyx is apparently quite constant for the species. 

 Having investigated such characters quite carefully, I find them to 

 be of considerable utility, for instance, in distinguishing between 

 closely similar but different congeneric species. The calyx is located 

 at the anterior end of the poison gland, presumably drains it, and 

 releases the venom to the poison canal. 



Though he made effective use of the poison calyx, Verhoeff over- 

 looked the poison gland as a source of classificatory information. My 

 own study of the poison gland is still in the initial stages ; however, it 

 seems clear that the gland can often provide valuable auxilliary clues 

 to identity at all levels from the specific to the familial. 



Generally speaking, the degree of development or size of the poison 

 gland seems inversely proportional to the development of the pre- 

 hensorial telopodite as a whole. When the prehensor is large and 

 ponderous (in some chilenophilines and mecistocephalids) , the gland 

 is often quite small and is restricted entirely to the body of the pre- 

 hensor itself. Convei'sely, when the prehensor is tiny and fragile 

 (in some ballophilines and geophilines), the gland is relatively exten- 

 sive and often passes from the telopodite back into the associated 

 prehensorial segment, I have observed exceptions to both rules, but 

 in the main this inverse relationship seems ^videspread. 



Both the calyx and the attached gland are readily seen if the whole 

 prehensorial segment with telopodite attached are mounted in Hoyer's 



