NO. 14 



INSECT ABDOMEN SNODGRASS 



37 



The morphology of the external genitalia of the phalangids has not 

 been determined from embryological studies, but there can be no 

 doubt that the cuticular parts, including the genital chamber, the geni- 

 tal organ, the duct of the latter and its bulb, are all derived from the 

 ectodermal genital chamber (" uterus externus ") of other arachnids 



Dct 



Fig. 13. — Phalangida: body segmentation and genital organs of Liobunum. 



A, ventral surface of body and appendage bases of a male, showing anterior 

 position of gonotreme (Gtr). B, genital organ of male (penis) retracted in 

 genital chamber, dorsal view. C, penis, lateral view. D, genital organ of female 

 (ovipositor) retracted in genital chamber, dorsal view. 



a, apical point of ovipositor ; Ap, apodeme ; b, b, lateral sclerites in wall of 

 genital chamber ; Dct, exit duct of ovipositor ; GC, genital chamber ; IXS, 

 sternum of ninth segment; mcl, muscle; Ovp, ovipositor; pmcl, protractor 

 muscle of penis; rmcl, retractor muscle; Pen, penis; XIV-Xl^I, posterior 

 somites. 



(compare I and J of fig. 4). The inner duct (Den) opening into the 

 bulb from the gonads is a mesodermal ductus conjunctus ("uterus 

 internus "). The muscular bulb and the exit canal constitute an ejacu- 

 latory apparatus comparable with the male ductus ejaculatorius (K, 

 Dej) or with the female oviductus communis (M, Ode) of other 

 arthropods. In most of the Phalangida the genital organ (penis or 

 ovipositor) has a closely ringed structure, and ends in two small 



