CEPHALOPODA FEOM THE CALCUTTA MUSEUJM. 13 



admirably described by M. Joubin (2). This apical jirolongation of the mantle is shorter 

 than in the latter species, and moreover is provided with a lateral fin on each side {ap-f.), 

 a character which distinguishes the present species at once from any hitherto described. 

 The mantle is laterally compressed, forming slight median longitudinal upper and lower 

 ridges. Dorsally the mantle-edge is produced in a point above the neck ; below it is 

 raised opposite the funnel. The fins are wide, the outlines of the right and left together 

 forming an almost perfect circle {f, fig. 51). 



The funnel, provided with a large internal valve, is fixed to the head without distinct 

 bridles, and at its posterior edge carries two sockets, each possessing two prominent lobes 

 fitting into corresponding depressions in the mantle (fig. 56, a Sc h). 



The head is small ; the eyes moderately large and without sinus. About halfway 

 between each eye and the attachment of the si2)hon is an olfactory jjapilla {olf.p.), about 

 2 mm. in length. The buccal membrane is well developed, with seven lobes and ridges. 

 The mandibles are very sharp (fig. 54, a & h) ; the ujiper mandible has a basal tooth on 

 either side {bt., fig. 54^), corresponding to which are small teeth on the lower mandible. 

 The radula consists of seven rows of teeth (fig. 57), closely resembling those of C. Picteti, 

 Joubin (2). 



All the arms are somewhat square in section, and are provided along the upper and 

 outer edge with a membrane very narrow in the first two pairs, absent in the third, and 

 very broad in the fourth (;«). The third and fourth pairs have narrow membranes along 

 the lower and outer edge *. 



Two rows of small suckers are placed rather far apart along each arm (rather more 

 closely set on the dorsal than on the ventral arms). Each sucker is obliquely set on a 

 slender stalk, and has a narrow opening, the horny ring of which is armed on the distal 

 side with square teeth (fig. 55). The soft rim of the sucker is more or less raised uj) 

 into a peak above the toothed horny margin (fig. 55). On the ventral arms, at the base 

 of the outer row of suckers are convex pigmented patches, no doubt similar to the 

 " vesicules refringentes " described by Joubin in Ch. Veranyi (3). 



The tentacular arms, which have unfortunately lost their clubs, are long and slender, 

 bearing at intervals the modified flattened suckers characteristic of the genus. 



The pen was somewhat injured owing to the contraction of the mantle. It is very 

 long and narrow (fig. 52, a & h) ; the hollow cone reaches halfway up and opens by an 

 oblique aperture. Diagrams of transverse sections of the cone and of the anterior region 

 are given in figure 53, a & h. The pen thus closely resembles that of Ch. lacertosa, 

 described by Verrill (9), and of Ch. Picteti ; yet the portion in front of the cone is 

 not tubular, as figured by Joubin for the latter species Ch. Vei'anyi, on the other 

 hand, has hitherto been described, by d'Orbigny and Ferussac (5), and by Verany (8), 

 as possessing a pen flattened and expanded at both ends. On examining a siDecimen 

 from the Mediterranean, I find, however, that its pen resembles in every essential that 

 of Ch. macrosoma here figured ; in the case of the works referred to, the artist probably 

 flattened out the slender cone before drawing it. 



* These membranes correspond rather to the keels in other forms, as they do not spring directly from the 

 sucker-bearing surface of the arm. 



