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



fissures, offsets from the chief one, pass away laterally into the 

 masses subdividing them into numerous lobules of varying form 

 and size. The lobules are connected together by fine filamentous 

 tissue, in which lie the branches of the oviduct and of the ovarian 

 artery. Each lobe is invested by a delicate membrane, and ap- 

 pears to consist entirely of a congeries of ova inclosed within very 

 delicate irregularly-shaped polygonal cells. PI. IV. fig. 1 a repre- 

 sents these cells with the ova at a very early stage of formation ; 

 b, ova somewhat further advanced ; c, ova much more highly 

 developed, showing the germinal spot surrounded by the pellucid 

 zone. 



The ovary is attached to the skin by what appears to be deli- 

 cate cellular tissue, and here and there by fine but firm flat bands 

 that seem to be continuous with the "inner or muscular layer of 

 the integument. Small tubes, which we think are veins, are also 

 seen passing from the outer surface of the organ into the sub- 

 stance of the skin. 



At the front of the ovary, the oviduct, PL III. figs. 1 & 2 e, re- 

 sulting from the union of the lesser ducts from all the lobules, is 

 seen to issue from the longitudinal fissure ; it is there a minute 

 opake tube, but soon dilates, and passing over the spermatheca is 

 bent upon itself two or three times very acutely, being further 

 considerably increased in diameter,/; after this it becomes rapidly 

 diminished in size, e', straight, and continued forwards along the 

 fissure between the lobes of the mucus-gland, and dipping down 

 it receives the constricted part of the testis near k as before men- 

 tioned, and is then suddenly bent back upon itself. After this 

 it is joined by the duct of the spermatheca, i, and the tube re- 

 sulting from this union turns immediately forwards, and after a 

 short course bifurcates, as is shown at fig. 2 m ; one branch, n, 

 the shorter, dipping downwards, is lost upon the channel belong- 

 ing to the right side of the mucus-gland, and into which channel 

 it appears to empty itself as the termination of the oviduct ; the 

 other and longer branch, i', is continued on to the third and 

 smallest external orifice by the side of the female aperture, and 

 appears to be the channel of the spermatheca. This latter branch 

 we have not been able to trace so satisfactorily as the rest, but 

 have no doubt of its existence as described. 



We now come to the large semipellucid or mucus-gland pre- 

 viously mentioned, figs. 1 & 2 g g. An analogous organ exists in 

 Doris and Tritonia which has been described by Cuvier as the 

 testis. It appears on looking first at the upper surface to consist 

 of two distinct glands, but on the under surface these are seen 

 to be perfectly continuous with each other. It is more or less 

 convex on all sides, but the upper surfaces are so inclined towards 

 each other as to leave a deep fissure, in which are lodged, as be- 



