Prof. G. J. AUman on the Anatomy 0/ Actaeon. 151 



sally diffused over the soft and constantly lubricated skin of the 

 mollusk, yet it would appear that the tentacula are specially ap- 

 propriated to its exercise. These organs consist in auriform 

 expansions rolled into a cylindrical tube, PI. V. figs. 1 and %, but 

 capable of being to a certain extent opened out at the will of the 

 animal. They are incapable of undergoing any true retraction, 

 but may be slightly shortened and thickened, in which condition 

 they present a number of transverse rugae. They are supplied 

 with large nerves from the supra-oesophageal ganglia. No fact 

 has thrown any light upon the question whether another sense 

 besides that of touch has also its seat in these organs. 



The entire surface of the skin is copiously lubricated with a 

 thick mucous secretion, which is poured out in large quantity 

 when the animal is irritated. The source of this fluid would seem 

 to be in certain pyriform bodies, PL VII. fig. 3, which are found 

 in considerable numbers beneath the integument. Each termi- 

 nates in a sinuous duct, which after running for some distance 

 beneath the skin, opens, most probably, upon the surface. These 

 organs are described and figured by Quatrefages, but the French 

 naturalist is in error when he speaks of them as the source of 

 the beautiful metallic tints with which the surface of our moUusk 

 is adorned. These tints are due to a pigment inclosed in distinct 

 cells, arranged in irregular groups beneath the epidermis, consi- 

 derably smaller than the bodies just described, and evidently 

 without any duct or external communication whatever. I am 

 unable to bring forward any observations of interest relative to 

 the senses of taste and smell in Actceon. 



Generative system : Embryology. — The reproductive system of 

 Actaon is one of great complexity, and one in which there must 

 be great difficulty in assigning to each part its proper function. 

 Actaon is hermaphrodite. A pyriform body, PI. VI. /, placed 

 anteriorly and at the right side, would seem to be the male in- 

 tromittent organ. This body is furnished with a tubular perfo- 

 ration which occupies the axis, and leads from the apex into an 

 oval cavity, v, situated in the base. From this cavity a sinuous 

 tube, or vas deferens, w, may be traced backwards, which, after a 

 course of considerable length, communicates with an oval body, x, 

 to be presently described, and then pursuing its course backwards 

 may be seen to bifurcate, one branch passing to the right and the 

 other to the left. Beyond this point I have in vain attempted 

 to trace the course of the tube. Its whole internal surface is 

 thickly clothed with cilia, whose presence is rendered manifest 

 by the constant rotatory motion imparted to the granular fluid 

 with which the tube is filled. 



Occupying a median position in the posterior part of the body 

 is an oval sac, y, near whose anterior extremity two tubes may be 



