BATHYDORIS. 13 



at all transparent, the internal organs adhere to the rather thin skin and affect the 

 colour in places. Length 41 '5, breadth 28 '7, weight 23 mm. The foot has a 

 maximum breadth of 23 mm., and is only 23 mm. long, the rest of the ventral surface 

 being taken up by the very large buccal parts. 



The front of the foot is deeply grooved ; the angles are not at all produced, at 

 least as preserved, but the groove runs down for about 8 mm. on each side. The 

 lateral and posterior margins are crinkled and drawn up against the body, but apparently 

 formed a free projecting edge about 5 mm. wide. Posteriorly, this edge is prolonged 

 into a short inconspicuous tail. 



The dorsal margin does not project, but is clearly marked about 4 mm. above the 

 foot by a line of papillae, the largest of which are about 2 mm. high. They are 

 detachable and leave behind them a mark like Q. A few under the rhinophores are 

 larger and nearly 4 mm. long. These papillae are most numerous near the dorsal 

 margin, but it would appear from marks left that they once covered the whole dorsal 

 surface, at intervals of two or three millimetres. There are also remains, especially 

 near the margin, of a reticulate pattern formed by low whitish lines connecting the 

 papillae, but it is not conspicuous. The papillae are rather irregular in outline, and 

 taper abruptly, but are not ramified. 



As preserved, the front of the animal is unlike B. abyssorum and B. ingolfiana. 

 The dorsal margin of papillae is continued anteriorly at a height of about 4 mm. above the 

 lips. Above this margin rises a sort of forehead 7 mm. high, and bounded on the top 

 by a thick ridge. It bears papillae, and seems similar to the rest of the dorsal surface, 

 from which it is divided by the ridge. The whole formation is possibly due to 

 distortion. The lower side of each large lip is prolonged into a thick tentacle. The 

 free part of the left tentacle, which is less contracted than the right, is 5 mm. long and 

 4 mm. thick at the base. These processes rise from the outermost corners of the head, 

 not from the sides of the mouth, and should perhaps be regarded as flaps of the head 

 rather than true tentacles ; they are not grooved. 



The rhinophores are bent, about 8 mm. long, and bear about thirty distinct 

 perfoliations. Both have on the outside a groove across which the perfoliations extend. 

 There is no trace of a pocket. At the base of each rhinophore is an inconspicuous flap 

 of skin, but it looks like an unusually large perfoliation rather than a sheath. About 

 20 mm. from the head is a large prominence on which are seated the reproductive 

 orifices. It lies just under the dorsal margin and is not surrounded by folds. 



On the posterior slope of the body are the branchial tufts, eight in number, and 

 arranged rather irregularly in an incomplete circle about 10 mm. in diameter and open 

 behind. About 5 mm. behind the circle lies the large anal papilla, 4 5 mm. long and 

 3 mm. thick, with an irregularly creuulate margin. Within the circle lies the sub- 

 central renal pore. The branchial tufts are composed of several (generally four) smaller 

 tufts, each of which consists of two or three short, thick, coarsely bipinuate plumes. 



When the dorsal skin is removed it is clear that there are no pockets into which 



