498 Mr. C. R. Narayana Rao on the Anatomy of 



Clitellum well marked over 4^ segments (10, 11, 12, 13^ 

 and 14/2) . In the living specimens the grey of the clitelhim 

 forms a striking contrast to the general blue background of 

 the body ; a very deeply marked glandular fold on the sides 

 of segments 10 aud 11 forming a sort of copulatory bracket 

 round the genital orifices. Between these folds in the 

 median line are more or less clearly defined oval elevated 

 glandular swellings on somites 10, 11, and 12. 



The genital area varies markedly in individuals of different 

 degrees of sexual maturity. In the fully mature forms the 

 region between the male apertures, i. e. the ventral part of 

 somites 10 and 11, may be completely hollowed out and 

 dark, which is occupied by glandular swellings in slightly 

 less mature forms. It is noticed that in several large 

 individuals the clitellar lateral folds on segments 10 and 11 

 are either feebly indicated or are not developed. It is in 

 the fully mature forms that the clitellum itself extends over 

 half of the segment 14, while in others only four segments 

 are aff"ected. The other grooves and depressions present on 

 the ventral surface of the genital area must be due to the 

 disproportionate clitellar thickenings. 



The male aperture is a large transverse slit between 

 segments 10 and 11, situated on spherical tumid elevations 

 in the furrow on or slightly external to seta-line b. Female 

 apertures between segments 11 and 12, inconspicuous, 

 internal to seta-line a. The spermathecal orifice in furrow 

 7/8, not easily visible, in line with the male openings. 



Internal Anatomy. — There are no septa between somites 

 1 and 2, and 2 and 3. Those between 3 and 4, 4 and 5 are 

 fairly, and others (5 and 6, 6 and 7, 7 and 8, 8 and 9) con- 

 siderably thick. In some specimens the se^ita QI7, 7/S, and 

 8/9 are only as thick as the anterior ones. 



The Muscular System. — The internal longitudinal muscles 

 are tough, and are far more powerfully developed in the 

 anterior somites, where they are iridescent. In somites 9 to 

 12 are laid additional innermost transverse bands of muscles 

 such as are described in D. robusta, subsp. indica (Benham). 

 The oesophagus is a thin-walled narrow tube extending up 

 to somite 13, Gizzards from 3 to 5 with softer annuli 

 between them are placed in somites 14 to 21, The first 

 gizzard is usually small and thin-walled. The alimentary 

 canal is thin-walled, and bears dorsally finger-shaped 

 appendages which commence from behind the last gizzard. 

 These glandular structures, which we may term "enteric 

 appendages," in the same position as the " lymph 

 glands^' of other worms like Pheretima, occur in most 



