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



in the various species, and from the variety and brilliancy of their 

 colouring form the chief attraction of these very elegant animals. 

 These prolongations appear on a superficial examination to be 

 creca, but when investigated imder favourable circumstances and 

 with a lens, they are found to be tubes with more or less compli- 

 cated follicular walls, PI. IV. fig. 9 a : the upper extremity of the 

 tube, where the follicular structure ceases, becomes suddenly deli- 

 cate, transparent and minute, fig. 9 b, and is continued on to com- 

 municate with a minute ovate vesicle, fig. 9 c, which lies within 

 the extreme apex of the papilla, and opens externally by a minute 

 circular foramen, fig. 9 d : the inner sm'face of the follicular or 

 glandular part, which we take to be the liver, is lined with a gra- 

 nular matter. 



The simplest form of this peculiar organ is met with in E. con- 

 cinna, PI. IV. fig. 1. In this species it is a mere dilated tube with 

 its wall slightly waved, and having the inner surface sprinkled 

 with darkish granules. In E. Farrani, fig. 2, it still maintains a 

 considerable simplicity of structure, but becomes decidedly sac- 

 culated, and with some degree of regularity. The complexity of 

 this organ is however much increased in E. olivacea, fig. 3, in 

 which it is deeply and regvdarly produced into follicles or sacculi, 

 which are much and variously puckered ; but in E. j)apillosa, 

 fig. 4, it appears to attain its highest development. The central 

 channel is somewhat tortuous, and gives oif on all sides variously 

 sized, irregularly shaped blind sacs, which are crowded with little 

 compound follicles. The whole of the inner surface of this com- 

 plicated biliary organ is lined with a thickish layer of what ap- 

 pears to be a granular substance through an ordinary magnifier, 

 but which on examination with the microscope is found to be 

 composed of large irregular vesicles or globules, PI. V. fig. 7, 

 disposed without any manifest arrangement, and filled mth nu- 

 merous granules. These last when submitted to a still higher 

 magnifying power are seen to be transparent, rounded, and of 

 various sizes, and nucleated, fig. 8. The larger bodies or glo- 

 bules have a diameter of yjo yth of an inch. The largest of the 

 granules measm-e about j^ o jjth of an inch in diameter. 



The compound follicular nature of this gland is best observed 

 in the living papilla fresh plucked from the animal, and submitted 

 to a slight action of the compressor. In papillae that have been 

 some time in spirits the gland is somewhat contracted, its divi- 

 sions approximated, and thus a more uniform surface of follicles 

 is presented. 



In describing this gland or hver M. de Quatrefages has the 

 following passage : " Mais les c?ecums qui partent des branches 

 de I'intestin pour penetrer dans les cirrhes s'entourent, en en- 

 trant dans leur cavite d'une espece de fourreau irregulier forme 



