504 MR. F. E. BEDDARD ON THE 
visible, and they appear to open separately on to the exterior; however, in 
Acanthodrilus, a Postclitellian worm, there are four male apertures instead of two, 
so that, after all, there would be nothing so very remarkable in finding the same 
thing in Plewrocheta, though their being so far in advance of the testes would — 
seem to throw some doubt on the hypothesis of their being vasa deferentia. 
The histological structure of the fimbriated expansion is shown on Plate 
XXVI. figs. 14, 18; the last figure shows the columnar epithelium from above, 
the cells are seen to be of a polygonal contour ; in transverse section (fig. 14) this 
layer of columnar cells with their cilia is seen, beneath is a layer of connective 
tissue which is crowded with blood-vessels. This extreme abundance of blood- 
vessels is very characteristic of these organs ; when viewed entire from above, the 
epithelium is seen to cover a plexus so closely pressed together that there is 
hardly any space between two adjacent vessels; this largely developed vas- 
cular supply makes it doubtful whether these organs may not be after all the 
only remains of the segmental organs left in the animal. 
On the opposite side of the mesentery, and corresponding with the anterior 
pair of fimbriated organs, are two small rosette-shaped glandular bodies (Plate 
XXVI. fig. 9) ; it is possible that these are the ovaries, though a careful histo- 
logical examination revealed none of the characters peculiar to those organs ; 
the absence, however, of ova may be perhaps accounted for by the fact that the 
animal was found in a burrow with its cocoon, which evidently had not long 
been deposited, and, accordingly, one would hardly expect to find the ovary, 
having for the time ceased from its function, to consist of anything more than 
a mass of indifferent cells ; a second pair could not be found; on the view that 
these are ovaries, we may consider the fibriated bodies as oviducts; but in 
this case we have the anomaly of four oviducts to two ovaries, and the 
absence, as In Anteus *), of vasa deferentia. 
There are four spermathece opening in pairs between the 7th and 8th, and 
the 8th and 9th segments. Their position is shown in Plate X XV. figs. 6,7 ; in 
the former figure, that of the posterior right hand spermatheca is considerably 
larger than the others ; this is drawn from one of the two specimens that I 
dissected ; in the other, all the four spermathece were as nearly as possible of 
the same size. 
Each spermatheca (Plate X XV. fig. 13) consists of two divisions ; the part 
opening externally is much smaller than the other, but has far thicker walls ; 
the chief part of the spermatheca has thinner walls. 
Cocoon and Embryos. 
Each of the specimens of Plewrochweta was found, as already stated, at the 
bottom of a deep burrow, together with a single egg-case; these two cocoons 
