66 



BULLETIN 100, UNITED STATES NATIONAL MUSEUM. 



tine, the first portion of the intestine lying along the esophagus. 



The distal, free end of the intestine extends back, as in Ritteria re- 



tracta, and R. picteti, to open 

 a little in front of and below 

 the atrial aperture. 



The condition of the neu- 

 ral glands and eye (fig. 39) 

 in the solitary Ritteria liexa- 

 gonahas not heretofore been 

 described. The disks of the 

 gland are well developed 

 (fig. 40). Their ducts (d) 

 are peculiar. Instead of 

 being a narrow coiled tube, 

 ;i3 in other species, each 

 duct is very wide, its diam- 

 eter being nearly half as 

 great as that of the dis- 

 coidal gland itself, and its 

 aperture to the pharyngeo- 

 cloacal chamber being of the 

 same width as the duct. 

 There are no distinct out- 

 growths from the ganglion 

 in connection with the 



glands, though one sees a broad protuberance (b) of the ganglion 



where each gland touches it. The cells in these protuberances are 



like the ordinary smaller cells of the ganglion. 



Fig. 39.— Ritteria hexagona, solitary form, dorsal 

 view of eye and ganglion; x 58 diameter. 



I '[<>. 40.-KITTERIA UEXAOONA, SOLITARY FORM, TRANSVERSE SECTION Ot EYE, GANGLION AND NEURAL 



GLANDS. X 47 DIAMETERS. 



The horseshoe form of the eye (fig. 39) is modified in this 

 species, the postero-lateral regions of the horseshoe being drawn 

 upward, making quite an angle, these regions being also enlarged. 



