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glands which are closely applied to its ventral, posterior and lateral 
surfaces. Its anterior angle is just visible in the figure which shows 
the lateral aspect of the accessory glands (Plate XXVII, fig. 2), and in the 
figure ol the ventral aspect of the male genitalia (Plate XXVII, fig. 1) 
the posterior margin is represented by the dotted line which crosses 
the middle portion of the accessory glands. 
Into the posterior angles of the seminal vesicle, the vasa deferentia 
open, and at the anterior angle, the sac opens downwards into a 
constricted space (Plate XXVII, fig. 3, c.g.com .) which forms a 
communicating passage between the seminal vesicle and the terminal 
portion of the common efferent duct which runs directly to the external 
genital opening. This constricted portion of the genital canal receives 
the openings of the ducts of the accessory gland, and appears to be 
the place in which the spermatophores are formed. The walls of the 
seminal vesicle are identical in their structure with those of the vasa 
deferentia. 
The Ductus Ejaeulatorius. 
Plate XXVII, figs. 1-3, c.g.com. 
This is the terminal section of the genital tract through which 
the products of the testis and the accessory glands reach the exterior 
of the body. Like the vagina of the female, its internal surface is 
lined throughout with a thin chitinous sheath which, at the external 
genital opening, continues directly into the general cuticle of the 
body. This chitinous intima is continued within the genital canal as 
far as the anterior opening of the seminal vesicle, and, therefore, the 
constricted space mentioned above, being lined with chitin, must there¬ 
fore be considered as a part of the ductus ejaeulatorius. The remaining 
portion is a flattened canal which runs directly to the external genital 
opening. In its general structure, the ductus ejaeulatorius closely 
resembles the vestibular portion of the vagina of the female. The 
chitinous layer of the ventral wall is very thin and flexible, while that 
of the dorsal wall is stout and attains a considerable thickness towards 
its lateral margins. 
The muscles of this part of the genital tract consist of two sets, 
one of which, the dorsal genital muscles , consists of a dense cluster 
of small bundles which originate from the ventral surface of the 
endosternite and are inserted into the proximal portion of the flat 
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