GONIODORIS. 



the vent on the median line about two thirds down the back. They, like the tentacles, are 

 non-retractile and are without lateral appendages. The foot is rather large, rounded in front, 

 and produced into a point behind. The generative organs have a single aperture, which is 

 situated on the right side, a little behind the dorsal tentacles. 



In its internal structure Goniodoris is not very dissimilar from Doris. The mouth opens 

 on the inferior surface of the head, whence a short channel leads into the buccal organ 

 (PL 17, fig. la), which, though not very large, is muscular, and has appended to its upper 

 surface a spherical gizzard {b), with radiating muscles, similar to that in Doris hilamellata and 

 others. The tongue is narrow, and composed of numerous rows of four plates each ; the two 

 plates next the median line bearing large curved spines with denticulated margins in G. nodosa .- 

 in G. castanea the margins are plain. There is no central spine or. plate. Not more than 

 half of the tongue is brought into action at a time, the posterior portion being tubular and 

 placed in a sheath which extends from behind the buccal organ : here the spines are 

 generated, as in Doris. The buccal lip is provided with a prehensile collar (fig. 2 a), 

 interrupted above, and crowded with numerous, minute, bifid spines (fig. 3). 



The oesophagus (fig. 1 d), which is rather long and slender, passes from the upper aspect 

 of the buccal organ just behind the gizzard, and, after passing through the nervous collar, is 

 slightly dilated in G. nodosa, but in G. castanea is of equal caliber throughout. Two short, 

 folliculated salivary glands (c, c) open into the buccal cavity, one on each side of the 

 oesophagus. The stomach (e) is small, of an irregular form, situated in a shallow cleft in the 

 anterior border of the liver. The oesophagus enters it in front, and the intestine [g), which 

 is a simple tube of no great diameter, passes off from the upper aspect, and crossing the 

 upper surface of the liver, dips down on the right side on its way to the anal nipple, situated 

 in the centre of the branchial circle. The biliary secretion enters the digestive cavity by two 

 or three large orifices near to the oesophageal opening. No pancreatic organ has been 

 observed. The liver (/) is a large oval mass, filling up the posterior portion of the visceral 

 cavity, and having a shallow cleft in front for the reception of the stomach ; it is granular and 

 of the usual dark brown colour. 



The reproductive organs are constructed on the same plan as in Doris, but show some 

 interesting modifications of the component parts. The testis is divided into three well-marked 

 portions ; — next the intromittent organ {h), it is stout and tubular (i) ; some distance backwards 

 it suddenly contracts and becomes minute and duct-like {i") ; this second portion leads 

 to one extremity of a fusiform, glandular body («"), which is doubled upon itself, and has the 

 other extremity opening into the oviduct. The second portion seems deficient in G. castanea. 

 The gland-like portion of the testis has some similarity to that described in Doris coccinea. 

 The ovary {Jc, Jc) is spread over the upper surface of the liver, and presents a decidedly 

 dendritic structure, crowded exteriorly with numerous ovigerous follicles. The oviduct is at 

 first very slender (j), but, suddenly dilating, becomes excessively wide, and as it advances to 

 the anterior margin of the mucus-gland it is reduced at once to its original caliber before 

 receiving the extremity of the testis ; it shortly afterwards receives the duct (o) from the 

 spermathecse and thence dips down into the mucus-gland. The vaginal tube \m), is rather 

 wide and long; it is doubled upon itself, and before reaching the spermatheca is much 

 attenuated. There are two spermathecse, one very large {n), the other small {p), the former is 

 long and pyriform, the latter elliptical. The mucus-gland (/) does not differ materially from 



