MONILIGASTER GRANDIS, A. G. B. 347 
The Vascular System in some other Species of 
Moniligaster. 
The two main variations from the arrangement of this 
system in M. grandis which obtain among my species are: 
1. A supra-intestinal vessel may be present. 
2. The latero-longitudinal and subneural system may com- 
municate with two pairs of hearts instead of only one. 
In M. pellucida there is a supra-intestinal vessel (fig. 30). 
This means that the intestinal veins of certain segments—in 
this case Segments x—xvi11—instead of opening into the dorsal 
vessel by means of dorso-intestinal vessels, collect into’a special 
trunk—the supra-intestinal—which, after receiving all the 
blood from the latero-longitudinal and subneural system, com- 
municates with the most posterior pair of hearts; the dorsal 
vessel has no connection with these, they are therefore intes- 
tinal hearts.! 
The supra-intestinal vessel is practically a specialisation of 
the latero-longitudinal and subneural system. 
In M. sapphirinaoides, M. ophidioides, and M. ro- 
busta the latero-longitudinal and subneural system communi- 
cates with hearts as in M. grandis, but in addition to vessels 
passing up to the hearts of Segment rx, as in the latter species, 
there is a similar pair opening into the hearts of Segment viit. 
This entails no other variations. 
In fig. 29 I have shown the way in which the subneural 
trunk communicates with the latero-longitudinals. There is 
always asymmetry in this region, the connecting trunk being 
always larger on the right hand side than on the left. The 
communication here is better developed than in M. grandis, 
but in neither case does it seem perhaps to be a very ample 
way of providing for the return of all the blood from the peri- 
pheral capillaries in the posterior region of the body to the dorsal 
vessel or hearts, but it must suffice for the purpose, and it 
1 Cf. Bourne on Megascolex coeruleus, in ‘Quart. Journ. Micr. 
Sci.,’ vol. xxxii, p. 64, footnote. 
