344 ON A HERMAPHRODITE AND 



Annelida were represented, in the present case, by lateral contractile 

 vessels which ran upon each side of the intestine, and gave off 

 transverse branches on to the dissepiments, from which twigs 

 proceeded dorsally and ventrally. 



The dimensions of these lateral vessels varied considerably ; 

 sometimes they were comparatively narrow, but in other instances so 

 wide as to appear to form a complete sheath around the intestine. 

 They contained a deep green, clear fluid, totally without corpuscles 

 or solid elements of any kind, while they themselves, when empty, 

 were usually quite colourless ; but I would draw attention to the 

 curious fact, which I have also observed in other annelids, that in 

 the anterior part of their course they occasionally present bright 

 green, granular particles, imbedded in, and adhering to, their outer 

 surface. 



The opacity of the anterior end of the animal, resulting from the 

 quantity of deep red pigment, prevented any very certain observation 

 of the manner in which these vessels terminate there. I am inclined 

 to think, however, that they open into a circular vessel, from which 

 the branchial vessels arise. 



It was no less difficult, in an adult specimen, to determine whether 

 a ventral vessel existed or not ; but in a young form, I saw such a 

 vessel communicating with the inferior transverse branches, and 

 distinctly contracting. It was superficial to the ciliated canal 

 immediately to be described. 



Of a dorsal vessel I could find no trace. The final ramuscules 

 of the superior transverse branches of the lateral trunks were found, 

 whenever they could be distinctly observed, to terminate ccecally. 

 There could be no question whatever, that these CEecal ends were the 

 natural terminations of the ramuscules, as the animal under obser- 

 vation had been subjected to no violence, and was viewed by 

 transmitted light. I am the more particular in insisting upon this 

 point, as one might very readily be led, in dissecting annelids, to 

 suppose that caecal terminations of the vessels are much more frequent 

 than they really are. Their vessels, in fact, possess, in a very high 

 degree, that tendency to contract when torn, which is so well known 

 in the arteries of the higher animals. And if under the simple 

 microscope the vessels of an Eunice or Nereid be deliberately pulled 

 asunder, it is most curious to observe how very little of the contained 

 fluid pours out, and how smooth and round the torn ends immediately 

 become. In our Protula, however, the mode of examination was 

 such as to preclude all chance of error from this source ; and I have 



