128 DR. J. STEPHENSON ON THE MORPHOLOGY, CLASSIFICATION, 



genus Draivlda occurs, perhaps, in Benham's description of 

 Moniligaster indicus ( = Dratoida rohtista Bourne), where it is 

 said (10) that septum 10/11 is thrown hack a whole somite, and 

 is confluent with 11/12 along a certain part of its course laterally, 

 but becomes separate towards the middle of the body {i. e., pro- 

 bably, towards the mid-dorsal and mid-ventral lines). This is, 

 however, not the condition of the " ovarian chamber '"' which I 

 wish to describe. 



Bourne (11) describes an arrangement of the septa which 

 results in the cavity of segment xi being reduced to two sacs ; 

 one of these contains the ovaries and nephridia of the segment, 

 and into it the oviducts open internally ; the other sac contains 

 the portions of the dorsal vessel, alimentary canal, and ventral 

 vessel which belong properly to the segment. The description is 

 not clear, nor does the figure solve the difficulties. 



Michaelsen (13), describing D. willsi and D. nejmlensis, speaks 

 (in the latter case with doubt) of an ovarian chamber formed by 

 septa 10/11 and 11/12, and a fine connecting membrane; the 

 chamber is thus a separated-off portion of segment xi. In a 

 subsequent paper (14) he seems inclined to recognize the ovarian 

 chamber as itself the xith segment in D. travancorensis, matthai, 

 and ghaiensis. Cognetti states (11a) that D. fakir has the 

 ovaries enclosed in a thin-walled peri-oesophageal capsule. 



I have myself recorded the relations of the female organs in a 

 number of species (21, 22, 23, 24, 25), and have found that the 

 condition is not the same in all. Some species have nothing note- 

 worthy in the arrangement of the septa in this region {B. pellu- 

 cidus var. steivarti, D. kanarensis). The complete ovarian 

 chamber found in D. roUmgana, kempi, rohusta, rangainatiana, 

 nepcdensis, ghatensis, decourcyi, harivelli var. impertibsus, and in 

 Moniligaster deshayesi, is produced by the two septa which bound 

 the somite containing the ovaries and funnels coming together 

 and f usino-, except over a horseshoe-shaped space which spans the 

 alimentary canal above ; the canal passes through an opening in 

 a membrane which represents the fused septa 10/11 and 11/12, 

 and a needle can be passed above it and below the ovarian cham- 

 ber without doing any injury to the chamber or any organ. In 

 a few species {D. hodgarti, affinis, pa2nllifer, chaiakiKliana) the 

 septa concerned in the formation of the chamber are not fused in 

 the dorsal part of their extent ; the consequence is that while the 

 chamber is formed below in the manner just explained, and spans 

 the alimentary canal as described, it reaches and is bounded by 

 the dorsal parietes above. In two species {D. hrunnea and 

 paramhikulamana) the septa meet above exactly at the dorsal 

 parietes, so that the chamber is just and only just excluded from 

 the dorsal body- wall. 



As shown by sections, the condition (in this worm at least) is 

 somewhat more complicated than was imagined, on the basis of 

 dissections, by either Michaelsen or myself. 



In the present species (fig. 4) there is dorsally in place of 



