314 PROCEKDIXGS OF THE MALACOLOGICA.L SOCIETY. 



are separate and quite at the posterior end of the body. As preserved 

 in this specimen they are not of the same length. Each is wing- 

 shaped and transversely elongate, and though fairly well-, is not 

 sharply-defined. That on the right (,9) is about 83mm. long, and 25 mm. 

 broad at its widest part ; its line of attachment is about the same as 

 the width of the tin, the distal end obtusely pointed and slightly 

 recurved ; the proximal half of the anterior border is feebly concave 

 and the distal half slightly convex, whilst of the posterior border the 

 middle portion is feebly convex, the proximal and distal thirds faintly 

 concave ; the fin on the left side (h) is rather larger than that on the 

 right, its anterior and posterior margins are nearly parallel, it is 

 about 120 mm. long and 30 mm. wide, and its distal end is obtusely 

 pointed and recurved. The dorsal part of the mantle-margin [e), which 

 alone can be seen, is on the whole feebly convex, with a faint 

 concavity on each side of the median third. In this (the dorsal) 

 aspect of the animal the siphon (being on the ventral side) is naturally 

 not shown, and it may be fortunately for the rest of the fossil, there 

 are no traces of tlie ink-bag and no discoloration due to the spilt ink. 



The Head appears to have been narrower than the body, probably 

 only about 40 mm. wide; a smooth oval-shaped area (i), 19mm. x 

 11 mm., immediately beneath the base of the arms, on the left of 

 the median line, with its major axis ])laced longitudinally and 

 slightly inclined towards the median line, probably indicates the 

 position of the left eye ; whilst a similarly-situated lenticular 

 impression (/), 1 8 mm. X 8 mm., on the right of the median line, 

 apparently indicates the position of the right eye. 



The Arms, eight in number, are disposed almost symmetrically 

 with respect to the body. That there are four pairs is quite clear, 

 but they are all so much flattened that their sequence is somewhat 

 obscure. There does not seem to be much doubt that the irregular 

 stellate mass, partially filled with calcite, indicates the position of 

 the buccal mass (/.;), the somewhat irregular projections from it being 

 the remains of the points of the buccal membrane. A thickened 

 V-shaped mass, having its obtuse point directed backwards, and at 

 about 30 mm. in front of the centre of the buccal mass, evidently 

 represents two thick arms («', «»') with their bases attached. Each is 

 about 11 mm. wide, and, tapering rather rapidly, appears to have been 

 about 55 mm. long. A very indistinct forwardly-concave curve {I), 

 at about 33 mm. from the extreme base of the united arms, may 

 indicate the margin of a web joining the two arms. Compared with 

 the other arms these appear to have been relatively short and stout. 

 Since they appear to be overlaid by the other arms, and remembering 

 that the dorsal surface of the animal is uppermost, it seems safe to 

 assume that they were the ventral pair. Near the buccal mass is 

 a smooth area from which arise two smooth areas, each approximately 

 15 mm. wide; these pass over the short, stout arms with their inner 

 margins about 17mm. apart; they slowly diverge at an angle of 

 about 18° until at about 65 mm. from the buccal mass, from which 

 point they gradually converge, when they meet and are superposed. 

 Each can be traced for a length of about 150 mm. from the buccal 



