376 W. BLAXLAND BENHAM. 



regions. In Plutellus Perrieri^ I have noticed a some- 

 what similar thickening of the ventral body-wall, due, how- 

 ever, to the greater development of only the longitudinal coat. 

 The longitudinal coat is, in Moniligaster indicus, inter- 

 rupted by four continuous grooves, visible on simple dissection. 

 It is in these grooves — marked i. ch. and o. ch. in fig. 7 — that 

 the chsetophores are situated. On the ventral side of the lower 

 groove is a special bundle of longitudinal muscles (v. long, mus.) 

 which appears to run throughout the greater part of the worm, 

 though I am not certain whether it extends forwards into the 

 genital region, for I cut only longitudinal sections of this part. 

 The longitudinal muscles exhibit a pinnate arrangement so 

 well known in the group, but only in its thicker portions j it 

 gradually merges into an irregular arrangement dorsally and 

 ventrally (fig. 7). 



In some of the anterior somites peculiar bundles of muscles 

 traverse the body-cavity in an obliquely vertical direction, 

 attached at one extremity just within the ventral cheetophoral 

 groove, and at the other to the outer part of the dorsal surface 

 (fig. 6) . These muscles I have referred to in speaking of the 

 generative apparatus, and they are represented as seen in a 

 dissected specimen in fig. 3, These oblique muscles are 

 limited to Somites vii to x, for those which lie apparently 

 in Somite xi, morphologically, as I believe, belong, like the 

 atrium with which they are connected, to the preceding 

 somite. I have referred above to the suggested purpose of 

 these muscles. 



The septa present the same variability in thickness which 

 has been remarked in so many worms. In the present species 

 the three septa, vi/vii, vii/viii, viii/ix, are thick and mus- 

 cular, the remainder thin (figs. 3, 5). In other species of 

 Moniligaster we find the same three, or an additional one in 

 front thickened. 



I believe none of the septa are absent, as Bourne states is 

 the case for some of his species. Certainly on dissection 



* " Description of Three New Species of Earthworm," ' Proc. Zool. Soc.,' 

 1892, p. 136. 



