3O EISEN 



Characteristics. One of the best defined species. Not only is it 

 strongly characterized by its enormous spermathecae, but also by the 

 large accessory gland-complex opening through the penial bulb onto 

 an external penis, independent of the sperm-ducts. The blood is deep 

 orange. This is also the color of the blood of Af. fontinalis and M. 

 grandis, these three species being the only ones of this genus which I 

 have examined alive. 



DETAILED DESCRIPTION. 



Spermathecce (fig. nd). The large sac-like part of the ampulla, 

 which extends through many somites, is bent at a right angle against 

 the lower part, which carries the diverticles. For the sake of clear- 



FIG. 10. Mesenchytrceus franciscanus. 



ness this is not shown on the figure. In four specimens sectioned and 

 in two dissected the spermathecae agreed as regards form. In length 

 they varied, some ending into XI, others in XII. 



Spermiducal apparatus (pi. iv, fig. 4, and test-fig. 10 a). Fun- 

 nels large, extending either backward or forward through two somites, 

 nearly straight, and about 12 times as wide as sperm-duct. Sperm- 

 duct not much more than i times as long as the funnel ; much twisted 

 and difficult to measure. Atrium has the usual form. The part inside 

 the bulb about equal in thickness to the part outside the bulb. In the 

 latter open some eight or more small globular atrial glands. These 

 do not penetrate the penial bulb, but open in a circle all around 



