Messrs. Hancock and Embleton on the Anatomy of Eolis. 97 



gentleman's account of the genital organs of his Eolidina, we find 

 it to be very meagre and imperfect. He states at the commence- 

 ment that these are as simple as possible ; we have found them to 

 constitute that part of the organization which is the most com- 

 plicated and difficult to be understood. The copulative vesicle 

 he mentions, which he thinks analogous to that of insects, and 

 destined to receive and preserve the spermatic fluid of the same 

 individual, acting the part in fact of seminal vesicle, and which 

 he is tempted to believe renders the conjunction of two individuals 

 unnecessary, seems to correspond to the spermatheca : the only 

 other parts he mentions, the testis and ovary with their ducts, we 

 find great difficulty in identifying with the parts described as 

 such in our paper. That the congress of two individuals does 

 really take place, we have had abundant proof. 



In the latter gentleman's paper on Tergipes above-quoted, we 

 have a confused but more detailed account of these organs. The 

 Professor seems to have confounded the testis and ovary together, 

 owing to the action of the compressor ; for we cannot believe in 

 the development of spermatozoa in the female parts, and in this 

 we agree with his translator as well as in our conviction that the 

 ^' poches seminales '' are parts of a multiple testis. If this be the 

 true interpretation then, we find that in this section of the genus 

 there is a modification of the testis which does not exist, as far as 

 we know, in any of the others. Such a modification we think 

 not improbable, since we have observed a similar conformation in 

 Chalidis, a naked mollusk having considerable affinity to the 

 EolididcB, and placed as the lowest genus in M. de Quatref ages' 

 order Phlebenterata. The liver, as M. de Nordmann gives it, ap- 

 pears to be a part of the large mucus-gland we have described. 

 The urinary gland is perhaps the opake granular part of the 

 same. The testis is evidently the spermatheca, from its form and 

 contents. The " vessie muqueuse" would seem to answer to the 

 sac of the penis, and the short flexuous canal, which, coming from 

 the crytalloid (?) bodies of the foot, enters its posterior extremity, 

 iappears to indicate the duct of the true multiple testis. 



Organs of Circulation, 



These are a heart and blood-vessels. 



The central organ consists of auricle and ventricle with valves. 



The vessels are arterial and venous. 



The heart and the roots of the large vessels lie in the wide 

 cavity of a delicate pericardium, PI. IV. figs. 2 and 4//, c c ; this 

 is a very fine transparent membrane, difficult of detectionat first, 

 which is attached to the aorta just beyond its origin, and to the 

 three great venous trunks just before their union in their com- 

 mon sinus, the auricle. At the same parts its external surface is 



Ann. ^ Mag. N. Hist. Ser. 2. Vol. i. 7 



