1910] 



The Palpi of Male Spiders 



167 



my 



The Palpus of Loxosceles. — In certain genera of the true 

 spiders, the palpi are as simple as in the tarantula type. In 

 Loxosceles of the family Scytodidse, for example (Fig. 4), 

 although the bulb has migrated nearly to the base of the tarsus; 

 the bulb* itself is very simple in structure. The basal division 

 of the bulb is inconspicuous; the middle division is nearly 

 spherical, and the apical division is long and slender. Here 

 the receptaculum seminis is differentiated into the three parts 

 described above ; the reservoir is large, while the ejaculatory duct 

 is very slender. 



The Palpus of Dysdera. — In the 

 family Dysderidse two quite distinct 

 types of palpi occur. In Ariadna the 

 palpus resembles very closely that of 

 Loxosceles; but in Dysdera it is of a 

 very different form (Fig. 7) ; this is due 

 to the fact that the apical division of 

 the bulb is not slender, and is sharply 

 differentiated from the middle division, 

 its wall being much less densely chitin- 

 ized. But there is on each margin a 

 distinct sclerite; and this part of the 

 bulb bears distinct apophyses. At the 

 tip of the apical division there appears 

 to be the beginning of a separation 

 into embolus and conductor. 



A summar}^ of the parts of the tarsus in the more generalized 

 types of palpi of males is shown by the following table: 



Body of tarsus or cymbium, containing the alveolus. 

 Genital bulb. 



Internal parts. 



Receptaculum seminis. 

 Fundus. 

 Reservoir. 

 Ejaculatory duct. 



External parts. 

 Petiole. 



Basal division. 

 T^.liddle division. 

 Apical division or embolus. 



Fig. 7. Palpus cf Dysdera interrila 



