A NEW SPECIES OF MONILIGASTER FROM INDIA. 377 



some of the septa appear to have been lost; this is due to 

 the peculiar shifting of the septa first pointed out by Horst 

 and by Rosa. 



The three thickened septa are nearly in their normal position, 

 but are inserted in the body-wall slightly behind the inter- 

 segmental groove. The same is true for Septum ix/x, which 

 is bagged out by the sperm-sac. Septum x/xi is, however, 

 thrown back a whole somite ; it is confluent with the Septum 

 xi/xii along a certain part of its course laterally (fig. 5), but 

 becomes separate towards the middle of the body, and is there 

 inserted into the body-wall just in front of the groove xi/xii. 

 At the level of the atrium, however, it can be traced below 

 this organ to its insertion just behind the groove x/xi ; that is, 

 in a position corresponding to that of the preceding septa 

 (fig. 8). The Septum xi/xii, again, is inserted in a normal 

 position above the groove. There are, then, no septa absent 

 in the present species. 



Rosa's diagram of the arrangement in M. Beddardii shows 

 it to be much less abnormal than in the present species. 



In M. Houtenii, allowing for the fact that the various 

 organs are situated one (testes, spermathecse) or two (ovary, 

 ovisacs) somites further back, the arrangement is the same ; 

 i. e. Septum x/xi is attached to body-wall about the middle of 

 Somite xi, Septum xi/xii to the body-wall near the hinder 

 part of Somite xii, Septum xii/xiii close to hinder boundary 

 of Somite xiii and immediately in front of Septum xiii/xiv, 

 which has almost the normal position. 



Neither Beddard nor Michaelsen makes any remarks about 

 this shifting of the septa, which may turn out to be a normal 

 feature for the genus ; and as it occurs too in Desmogaster, 

 perhaps even for the family. 



The nephridia closely agree with those of M. Houtenii; 

 they commence in Somite iv, and are continued in each somite 

 in a regular manner, and the fact that only one pair of 

 nephridia occur in the wide stretch between Septum ix/x and 

 that which I have referred to as Septum x/xi confirms me in 

 this interpretation. 



VOL. XXXIV, PART IV. — NEW SER. C C 



