A NEW SPECIES OF MONILIGASTER FROM INDIA. 369 



than the ovoid prostate of M. Barwelli and M. Beddardii, 

 and unlike these is bound down to the body-wall by special 

 muscles ; if it were placed on end with its morphologically 

 dorsal (its actual posterior) end upwards it would resemble the 

 condition in Beddard's species. The hemispherical glandular 

 part is seen in sections to be provided with a duct dorso- 

 laterally compressed and underlying the glandular part. In 

 the other species, so far as is described, the prostate is 

 elongated, and is very large and extensive in M. Deshayesi. 



We have no information as to its shape, which is apparently 

 a good specific character, in any of Bourne's species. 



There is a very peculiar arrangement of muscles in connec- 

 tion with the atrium which has not hitherto been recorded in 

 any earthworm. 



A sheet of muscles, or rather a series of flattened bundles of 

 muscle-fibres, passes obliquely across the body-cavity from 

 their origin in the body-wall above the lateral line to their 

 insertion in the wall of the prostate. On dissection, when the 

 sides of the body are pinned down, this sheet is of course 

 horizontal ; in the natural position, however, it is an oblique, 

 transverse sheet, such as exists almost universally in the Poly- 

 chseta, where, however, it is generally in relation with the 

 cheetophores at its outer end. 



In Somite x, immediately in front of the atrium, a similar 

 sheet of muscles exists, reaching nearly to the level of the inner 

 chsetse ventrally, and having the same origin as that in Somite 

 XI. In Somites vii, viii, ix quite a similar arrangement 

 obtains, though, as we get forwards, the muscle bundles are 

 smaller and smaller. 



These recall the '' arciform muscles " recently described by 

 Cerfontaine^ in Lumbricus, but which pass, not from the 

 lateral to the ventral surfaces, but from one side to the other, 

 inserted at each end at the level of the ventral chaetse. Another 

 point of diflference there is, in that in Lumbricus these 

 muscles do not traverse the body-cavity — they are embedded 



1 'Arch, de Biol.,' x, 1890: " Eech. sur le syst. cutane et sur le syst. 

 musculaire du Lombric terrestre." 



