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The author observes generally, respecting the Vermes of Linnaeus, 

 that the blood is conveyed by veins to the respiratory organs, and 

 from thence by arteries to the heart, in which they differ from fishes; 

 while they differ, on the other hand, from Mollusca in general, by 

 having red blood. 



The Sepia has been thought to have a circulation peculiar to itself; 

 but the author remarks, that it bears a close resemblance to that of 

 the Teredo, in having two auricles which transmit the blood received 

 from the bronchise to the heart, but differs in this, that there are also 

 two auricles that receive the venous blood, and transmit it to the re- 

 spiratory organs. 



Observations on the Hirudo vulgaris. By James Rawlins Johnson, 

 M.D. F.L.S. $c. Communicated by the Right Hon. Sir Joseph 

 Banks, Sort. G.C.B. P.R.S. ead Nov ember 14, 1816. [Phil. 

 Trans. 1817, p. 13.] 



The animal here described under the name of Hirudo vulgaris, is 

 the same that has been denominated by Linnaeus and others, Hirudo 

 octoculata, on account of the number of its eyes ; but since the Hi- 

 rudo tessulata has also eight eyes, it has been thought proper to 

 change that name for one not liable to mislead. 



This little animal is found very commonly in rivulets, attached to 

 the under surface of stones. Its length varies from one inch to an 

 inch and an half. The back is of a dark brown, marked with nu- 

 merous transverse lines, and a central line longitudinally of a black 

 colour. On the belly also is a longitudinal black line, but the rest 

 is of a yellowish-green colour. 



In structure this animal very much resembles the Hirudo medid- 

 nalis, having the anus at the extremity of the tail, and four longitu- 

 dinal vessels destined to convey the circulating blood, one dorsal, one 

 abdominal, and two lateral. In these, eight pulsations are observable 

 in the course of a minute, but not derived from any central organ 

 corresponding to the heart of other animals. 



Its food consists of very small worms, which it swallows whole. 



The object of the present communication is to record such pecu- 

 liarities as the author has observed in its mode of propagation, to 

 which he has paid attention during the last two summers. 



Having found a pair of them copulating as hermaphrodites, like 

 the common snail, on the 13th of August, he watched the period at 

 which eggs were deposited, and found a capsule of eggs produced on 

 the 17th, and another on the 18th, both of which were subsequently 

 hatched. The same leech also laid as many as seven more capsules, 

 at intervals of two or three days in succession, but all these last seven 

 proved abortive. 



Those which were productive showed signs of life in three weeks, 

 and in five more the young made their escape from the capsule. 



The capsule in which the eggs are deposited is formed as a mem- 

 branous ring, surrounding the body of the parent in the region of 



