EELATION OF RESPIRATION TO CIRCULATION. 267 



granules forming three sides of a parallelogram about 

 the oesophagus, and two dark-brown irregular masses 

 above each oviduct. The hairs, or spines, are distri- 

 buted over the fins as well as over the body — an 

 arrangement which has been noticed by Khron, who 

 denies that they are setw at all, considering them to 

 be merely epidermic processes. On what grounds he 

 so considers them, I am not informed ; but I entirely 

 concur with him, because I find these supposed setw 

 very rapidly undergo decomposition, which would not 

 be the case were they inorganic hairs or spiculse. Let 

 me conclude these perhaps dry details with the re- 

 mark that the delicate layer of epidermis, composed of 

 rounded cells — the existence of which Krohn first dis- 

 puted and then admitted — was visible in my speci- 

 mens, although I mistook it for scales or scaly epithe- 

 lium ; and that I can confirm Huxley's statement of 

 the existence of a ciliated oviduct in the external part 

 of the ovary, if the statement of so accomplished a 

 zootomist needs confirmation. 



But the point of all others which in this interest- 

 ing Sagitta excited my interest was one I have not 

 seen noticed by others, namely, the entire absence 

 of any vascular system. Here is an animal with a 

 nervous system of some importance (see Prof Huxley's 

 diagram in the Microscopical Journal) with eyes, if 

 no other organs of sense, and with muscular fibres of 

 the striped kind ; yet in spite of such characteristics 

 of high organisation, it is totally without " blood, " 

 without a trace of a vascular apparatus. So striking 



