72 PROFESSOR LANKESTER. 



given by Dr. George Eolleston is, it would seem, due to his 

 having misunderstood the German authors. 



The statement that " the pseud-h?einal system commnnicates 

 with the perivisceral cavity so as to form a lacunar circulation" 

 in S^Uidia, the Ophelia, the Cirratulida, and the Staurocephali, 

 is more difficult to account for than is that relative to Branchivb- 

 della, since whilst there is here also no foundation whatever for 

 such a statement in fact, the description and figures of Claparede 

 with reference to two at least of these genera are admirable in 

 clearness and detail. We are driven to the conclusion that 

 Dr. George Rolleston has acquainted himself with the introduc- 

 tion, without having consulted the body, of Claparede^s work. 



The blood vascular system of Syllidia, Ophelia, the Cirra- 

 tulida, the Staurocephali, and the Terebellse, is a closed system 

 and contains blood in which float corpuscles. These corpuscles 

 are colourless and are not to be confused with the colourless 

 corpuscles existing in the open vascular system of the true 

 Leeches, nor with the corj)uscles coloured red by haemoglobin 

 which exist in the perienteric fluid of the anangian genera 

 Glycera and Capitella. Corpuscles similar to these last are met 

 with in the vascular fluid of some few Nemertines, in Phoronis, 

 in the single blood-lymph fluid of the Lamellibranchs, Area and 

 Solen (one species), and in the blood of Vertebrates. 



Whilst I regret to find myself unable to accede to the state- 

 ments in the text-book which I have quoted above, I may point 

 out that the errors therein contained are not traceable to any 

 attempt on the author's part to make original observations 

 in the domain of morphology, but are rather due to a failure 

 to observe accurately the contents of books. 



The corpuscles of the red blood of the Earthworm are 

 abundant in the larger and even in the finest branches of the 

 vascular system. They are flattened, fusiform bodies, usually 

 somewhat broader at one end than the other, sometimes nearly 

 circular. They vary in size from the -ry^'^-ijth to the ^-oVoth of 

 an inch in long diameter, but by far the majority are of a uniform 

 length of about 3-,j\,7yth of an inch. The corpuscles have a clean, 

 sharp outline, but occasionally what appears to be a small quan- 

 tity of ragged protojjlasm is seen beyond this sharp contour. 

 They are colourless, but stain feebly after treatment with dilute 

 osmic acid followed by jncrocarmin. A small centrally placed 

 granule receives, when tlie corpuscles are thus treated, a deep 

 staining. From a comparison with the structures presented by 

 the walls of the vessels in which these corpuscles occur, it is 

 clear that they are the nuclei of the endothelial cells set free 



