276 CALIFORNIA ACADEMY OF SCIENCES. [Proc. 3D Ser. 



at the anterior end of the segment. The arrow in figure 7 

 indicates the course of the intestine and genital duct. The 

 eighth segment is united by such a narrow membrane to the 

 ninth that no rotatory motion is possible between the two. 



The ninth segment is comparatively very large and highly 

 modified (figs. 1-4, ix). It is strongly compressed laterally 

 (fig. 3), and is ovate in lateral view (fig. 4), with the larger 

 end forward. The foramen from it into the eighth 

 segment (fig. 4, for.) is a large circular aperture on the 

 anterior half of the left side. There is no division of the 

 segment wall into tergum and sternum surrounding this 

 foramen. The ventral surface back of the vertical from the 

 anterior edge of the anterior foramen is invaginated so as to 

 form a deep narrow groove-like cavity, the genital cham- 

 ber, open below and posteriorly (fig. 3,^. c). From the 

 lower edges of the side walls there hangs downward on 

 each side a semimembranous fold. The anterior two- 

 thirds of each fold makes a wide curtain-like flap (figs. 3 and 

 4, cur.). The posterior part is narrow, and at the posterior 

 end projects backward as a small free lobe. From the free 

 posterior edge of each lateral wall of the genital chamber 

 there arise superiorly two slender curved chitinous appen- 

 dages (figs. 3 and 5, a and b), probably clasping organs. 

 The upper one («) is the larger and ends in several irregu- 

 lar lobes, the terminal one bearing a large recurved spine; 

 the lower one is angularly bent, and ends in a hammer- 

 head-like enlargement. Between the bases of the two pairs 

 there arises, from the posterior part of the roof of the cham- 

 ber, a median process (fig. 3, c. and fig. 8). This one is 

 thick basally, with a slender terminal finger. Arising from 

 the lower edge of the anterior wall is a large median ap- 

 pendage (figs. 3 and 4, s. ^.). It is rather thick basally, 

 tapers to a point terminally near the end of the hypopyg- 

 ium, and is deeply grooved above. It serves as a sheath 

 for the penis. The sides are partially concealed between 

 the two curtain-like folds (fig. 4). 



The penis (figs, i, 2, 3, 4, and 6, /•) ^^ ^ long slender 

 curved chitinous rod-like tube. It arises from a large base 



