Messrs. Hancock and Embleton on the Anatomy o/Eolis. 183 



under the microscope to be composed of two distinct, though 

 connate carpels ; the ovules are few, horizontally attached, or 

 somewhat pendulous from narrow axile placentie attached to the 

 twofold dissepiment. These are characters that secin to corre- 

 spond in great measure with the Bruniacea, with which the habit 

 of Lonchostoma does not ill accord. These are merely hasty 

 indications, as it would be foreign to the object of the present 

 investigation to pursue such inquiries farther. 



XIX. — On the Anatomy of Eolis, a genus of Mollusks of the order 

 Nudibranchiata. By Albany Hancock and Dennis Em- 

 bleton, M.D. 



[Continued from vol. i. 2nd Series, p. 105.] 



[With two Plates.] 



Nervous System. 



This is made up of central masses or ganglia united by com- 

 missures, and of nerves. The ganglia are five or six pairs, four 

 of which are symmetrically arranged wdth regard to the median 

 line, and together with their commissures surround the com- 

 mencement of the oesophagus lying upon the upper and poste- 

 rior surface of the buccal mass, vol. xv. PI. V. fig. 16 b and Fl. V. 

 fig. 1 of present paper. Two pairs are supra-oesophageal and two 

 infra-oesophageal. The former exceed the latter many times in 

 size. The masses are of a pale yellowish flesh-colour, and appear 

 to be filled with globular vesicles of various sizes. 



First, of the supra-oesophageal or cerebral ganglia, the median 

 pair, PL V. fig. 1 a «, largest of all, are irregularly ovate, flattened 

 above and below, and somewhat constricted about the middle as 

 if composed of two parts ; their anterior ends, which are the 

 larger and truncated, are united across the median line by a short 

 broad commissure. The second or lateral pair, b b, lie rather 

 behind the first and on the sides of the oesophagus ; they are 

 irregularly spheroidal, smaller than the first and flattened like 

 them, and intimately connected to their external posterior mar- 

 gin. The two pairs of infra-oesophageal ganglia are of very un- 

 equal size : the first or buccal, or larger pair, c c, are elliptical, 

 their long diameters placed transversely one on each side of the 

 median line, across which a short thick commissure unites their 

 contiguous ends ; from the under surface of these, at their outer 

 and anterior part, spring two short pedicles, supporting the 

 second pah* of ganglia, d d, the gastro-oesophageal, very small, 

 not one-fourth the size of the last, but of tlie same form, in 



