958 MR. H. R. MEHRA ON TWO NEW INDIAN 



duct are of a different appearance altogether. They are not of 

 the same uniform height throughout, being tallest about the 

 middle, where they are 8*5 /.i high ; they are 14"3 fx broad at the 

 base; the inner portion of the cell projects into the lumen and 

 contains the prominent rounded nucleus of 3*5 /j. diameter (text- 

 fig. 4 ; PI. II. figs. 6 & 7). The atrial duct in this region is 

 much thicker than in the proximal part, being about 28-4:0 fx 

 in diameter as it gradually descends towaixls its termination : 

 its lumen is 16-22 /x wide. Outside the epithelium there is a 

 covering of muscle fibres, which is slightly thicker than that 

 of the proximal part of the duct owing to the presence of 

 an additional layer of longitudinal muscle fibres external to the 

 circular layer. 



The paratrium, a blind tubular outgrowth of the atrium 

 characteristic of Branchiura, Kawamuria, and Bothrioneuron is 

 here absent. 



The spermiducal chamber is the median quadrangular depres- 

 sion on the ventral surface in the 7th segment formed as 

 an invagination of the body- wall. The term has been used by 

 Goodrich for a similar structure in Vermiculns. The chamber is 

 large, about 11 5 /a deep, 200-250 /^ long and about 360 /x broad; 

 the margin of its external opening is generally puckered. The 

 openings of the atrial ducts lie inside at its anterior angles, one 

 on each side, and in several specimens during life one or two 

 penes were seen projecting out of it ; sometimes, though rarely, 

 the chamber is everted to form a papilla-like structure bearing 

 the openings of the atrial ducts on its surface. The diameter of 

 the terminal portion of the atrial duct near its opening is about 

 32 fi, and the epithelial cells lining it gradually become of a 

 uniform size, till they have the same form as those lining the 

 inner wall of the chamber, which is the inturned epidermis. The 

 cuticle of the epithelial lining of the chamber is continuous with 

 that of the body-wall outside. The spermiducal chamber acts 

 probably as a sort of sucker during copulation. Although there 

 is no direct muscular mechanism for deepening the chamber, the 

 radiating muscle fibres attaching the muscular sacs to the body- 

 wall by contraction can indirectly pull it to a certain extent and 

 thus deepen it to produce a sucker mechanism. The chamber 

 was more deepened in the specimen in which the penis was pro- 

 truded ; and it appears that the contraction of the muscle fibres 

 of the muscular sacs, which lie on its top, helps in deepening the 

 chamber also. 



Penis. — While examining several specimens in the living con- 

 dition I saw in some cases one or two long cylindrical soft penes 

 projecting out of the spermiducal chamber for a long or short 

 distance. After proper fixation, sections were cut of two such 

 specimens and the structure of the penis was investigated. This 

 organ is covered externally by epithelium w^hich is really the 

 inner wall of the wide terminal portion of the atrial duct, and can 

 be distinguished as such by the peculiar character of its cells, which 



