68 



SMITHSONIAN MISCELLANEOUS COLLECTIONS 



NOL. 94 



Two pairs of small muscles lie within the aedeagus, both arising 

 within the base of the latter (fig. 25 B) ; those of one pair (^/p) 

 extend dorsally to the lateral plate (111) in the proximal part of the 

 dorsal lobe, those of the other pair {^80) are attached distally on 

 the ventral lobe. The other muscles of the aedeagus include the epi- 

 phallic muscles (2/8) already mentioned, which arise on the zygoma 

 of the apodemes, and muscles that functionally pertain to the 

 endophallus. 



The endophallus is mostly ensheathed in broad muscle plaques, 

 which make of the organ a strong muscular bulb, into which opens 

 the ejaculatory duct. The endophallic musculature comprises dilator 



IX X Eppfc Papt 



Phtr 



Rect 



Dej 267 IXS 



ej^ 



Fig. 26. — Median vertical section of the end of the male abdomen of Dissostcira 

 Carolina showing the retracted position of the phallic organs. 



and compressor muscles of the endophallus, and compressors of the 

 ejaculatory sac. The dilators of the endophallus include a pair of lat- 

 eral muscles (fig. 25 C, E, 281) and a pair of dorsal muscles (F, 282) . 

 The lateral dilators are wide sheets of muscle fibers arising dorsally 

 on the aedeagal apodemes (C, Apa), and extending ventrally and 

 anteriorly to the outer surfaces of the anterior apodemes of the lateral 

 endophallic plates (C, E, w). The dorsal dilators, which likewise are 

 broad sheets of fibers (F, 282), arise laterally on the inner margins 

 of the aedeagal apodemes and are inserted mesally on the dorsal 

 margins {x) of the endophallic plates. The single compressor muscle 

 of the endophallus consists of a thick mass of fibers stretched trans- 

 versely over the anterior end of the endophallic bulb (E, F, G, 28^) 



