206 Annals Entomological Society oj America [Vol. XII, 



tions of the seminal vesicles. Their epithelium is somewhat 

 similar to that of the vesicles and their musculature is the sarhe. 



Passing caudad to the union of this so-called ductus ejacula- 

 torius duplex, we find we have a change in the musculature, 

 which now takes on a longitudinal course. (Fig. 19). For 

 quite a distance the epithelium retains its uniform columnar 

 appearance. The longitudinal muscle is characteristic of the 

 ductus ejaculatorius simplex, which is the caudal portion 

 leading to the base of the penis. Undoubtedly this duct is 

 ectodermal in origin. It is an invagination of the hypodermis 

 and bears, for more than one-fifth of its length, a prominent 

 intima. Above the caudal fifth the chitinous lining becomes 

 thin and indistinct and is wanting at the juncture of the ductus 

 ejaculatorius simplex and "duplex." 



The longitudinal muscle, characteristic of the upper end 

 of the single tube, has added to it, a prominent layer of circular 

 muscle about half way along the duct (Fig. 20). The 

 circular muscle appears outside of the longitudinal. Toward 

 the caudal extremity the musculature becomes very uneven and 

 very prominent, till about the so-called "bulbus ejaculatorius," 

 it is very heavy, and interwoven. A third, outer longitudinal 

 layer is added (Fig. 21). Koschevnikow could not find 

 muscle in the ejaculatory duct of Apis mellifica. This seems 

 very strange, in view of the function of this organ. 



The epithelium of the ejaculatory duct goes through a 

 metamorphosis comparable with that of the vasa deferentia, 

 i. e., it forms pseudonidi, but these are covered over with the 

 intima. In the so-called "ejaculatory bulb," the epithelium is 

 actually folded, assuming the appearance of the epithelium of 

 the proventriculus. 



What by some authors is called the ejaculatory bulb is in 

 reality a continuation of the simplex duct, with abundant 

 muscle, with no enlargement, but a reduction of its lumen. 

 Its function is to force the seminal fluid through the chitinous 

 penis. 



CONCLUSION. 



(1) The Saturniid testis belongs to Chlodkovsky's second 

 (larval) type, consisting of four testicular tubes combined in a 

 common capsule. 



(2) The greatest changes take place during the pupal stage. 



