170 Anuiils Entomological Society of America [Vol. III. 



Till'. M'>K1 ^l'|-.( !.\l.l/i;i) I \ l'l-.> ()1 I'AI.IM. 



In the development of the bulb of the male palpus in the 

 more speeialized families of spiders there has been evolved an 

 exceedingly comijlicated organ, which is difTicult to understand, 

 on account of its small size and the fact that when at rest it 

 is comi)actly folded. Fortunately when such a pal])us is boiled 

 in a solution of caustic potash (10%) the h)ulb expands so that 

 its parts can be seen; and if preserved in glycerine, it remains 

 flexible, so that it can be easily mani])ulated. The expanded 

 bulbs figured below were prepared in this way. Even with the 

 best of preparations, it is sometimes difficult to make out the 

 relation of parts; this can be most easily accomplished by the 

 use of a stereoscopic binocular microscope. 



The extreme specialization of the palj^i of males is marked 

 chiefly by the development of ha^matodocha, to be described 

 later, and by an increase in the number of distinct parts and 

 appendages of the bulb. The maximum degree of specialization is 

 to be found in the Araneinae, of which the palpi of several species 

 of Aranea are described later. The understanding of the rela- 

 tion of the ])arts of the bulb in this genus will l)e facilitated by 

 a study first of a more simple form, such as is found in the 

 Linyphiida\ 



Thk LiNvi'iiiA Tvi'K o¥ PALi'LJs. — The very common Liuy- 

 phia phrygiajia will serve as an example of the Linyphiida?. 



As in Pachygnatha, just described, the body of the tarsus of 

 Linyphia consists of two parts; the cymbium (Fig. 10, cym.), 

 and the paracymbiiim (Fig. 10, p. c). The alveolus is a circular 

 cavity near the base of the cymbium. 



When the bull) is expanded, the three divisions of it are dis- 

 tinctly separatetl, there being a slender neck between the basal 

 division (Fig. 10, b. d.) and the middle division (Fig. 10, m. d.), 

 and also a similar slender neck between the middle division and 

 the apical division (Fig. 10. a. d.). 



The wall of the basal division of the bulb consists of two 

 parts; the basal haematodocha, and the subtegulum. 



Tlie basal hccmatodocJia.- The genital bulb is attached to the 

 cymbium, within the alveolus, by means of a saclike structure, 

 wliich, ordinarily, is inconspicuous or completely concealed 

 by other ]3arts of the bull), but which is very conspicuous in the 

 ex])anded bulb (Fig. 10, h. //.). This has been named the 



