496 MR. F. E. BEDDARD ON THE 
are given off from the dorsal trunk, which after joining a branch supplying the 
vascular plexus on the surface of the gizzard, and then giving off three other 
small branches, which are distributed to the mesenteries, dividing 7th from 
8th, and 8th from 9th segments, become united with the first arch—joining the 
dorsal and ventral vessels—before its division. This arrangement of vessels, as 
well as the vascular plexus on the gizzard, to be described shortly, is given in 
Plate XXYV. fig. 5. The supra-intestinal vessels, two in number, I was unable 
.to trace further forward than the 10th segment, or further backwards than the 
20th; they would seem to be equivalent to the single “ sus-intestinal” vessel 
described by Perrier in Pontodrilus, Perichwta, and Uvrocheta, which he 
regards as the only representative of the typhlosole left in these worms. 
In Urocheta and Pericheta, certain of the “ hearts,” or transverse contractile 
trunks connecting the dorsal and ventral vessels, are in reality connected at 
their upper end with the supra-intestinal, and not the dorsal trunk; these are 
termed by PERRIER “ cceurs intestinaux ;” the anterior hearts connecting the 
dorsal vessel proper with the supra-nervian trunk being distinguished by the 
name of “cceurs lateraux.” In Pontodrilus,* there are the same two sets of 
hearts, but the communications of the “ cceurs intestinaux ” are rather 
different ; there are occupying segments 5 to 11 inclusive, a pair of lateral 
hearts to each, and in the two following segments are two pairs of intestinal 
hearts readily distinguishable from the others by their greater size. These 
last mentioned are not only connected with the supra-intestinal trunk, as in 
Urocheta and Pericheta, but also have a delicate branch connecting them with 
the dorsal vessel. This same arrangement is described by PERRIER as existing 
in Titanus Forguesti, a representative of an entirely distinct group, that of the 
Intraclitellians. In the Ante-clitellian forms, of which the common earthworm 
is an example, there is no such differentiation of the hearts; they all alike 
connect the dorsal vessel with the supra-nervian. “ L’existence des cceurs 
intestinaux,” says Perrier, “parait bien reellement limitée aux Lombricidés 
intra et post-clitelliens,” but whether all worms belonging to these two groups 
are thus provided is another question. In Pleurocheta, which, from the 
arrangement of its generative apertures, and their relation to the clitellum, 
ought perhaps to be classed with the Intraclitellians, but is most certainly not 
Ante-clitellian, no trace of any intestinal hearts was to be found, though after 
making myself acquainted with Prerrier’s memoirs, I naturally looked very 
carefully ; still it is possible that the additional communication with the supra- 
intestinal vessel may be present ; but at any rate the communication of all the 
hearts with the dorsal vessel is perfectly obvious, so that, in this respect, 
Pleurocheta differs materially from Pericheta. 
At present our knowledge of the circulatory organs in the Oligochwtu is not 
* Perrier, Arch. de Zool. Exp.,-vol. ix. 
