CEPHALOPODA PBOM THE CALCUTTA MUSEUJM, 11' 



The sliort mantle tapers to a sharp point. The fins are rhomhoidal, with anterior 

 rounded horder and nearly straight posterior border ; they extend forwards more than 

 halfway up the mantle beyond the point of attachment. The head, of about the same 

 width as the mantle, is provided with large eyes, and fits less closely on to the mantle 

 than in the preceding species (this may be due to differences in preservation). A small 

 olfactory crest is situated behind the eye. The funnel has a valve, two well-marked 

 bridles, and l-shaped sockets. 



The buccal membrane has 8 lobes. 



The three dorsal pairs of arms are rounded proximally and slightly keeled distally. 

 The ventral arms have a lateral membrane on the upper side. Two rows of hooks are 

 borne by all the arms along almost their entire length. The ventral arms appear to bear 

 no suckers at all distally, but their tips are swollen, and pi'ovidedin both sexes with three 

 large convex pigmented organs forming a sort of club. These swellings are probably 

 phosphorescent organs ; they correspond exactly to the modified arms described by 

 Pfeffer in Enoploteuthis Iloylel, Pfelfer, and considered by him to be due to hectocotyli- 

 zation. The other arms bear, near their extremity, a small number of minute suckers, 

 the horny ring of which is armed on the distal margin with large teeth (fig. 49). 



The tentacular arm is slightly expanded to form a club, bearing in the middle region 

 four hooks on the lower side, and three hooks alternating with suckers on the upper 

 side (fig. 48). Beyond these are four rows of small suckers, with a wide ornamented 

 papillary area and a smooth margin (fig. 50). At the base of the club is situated the 

 connective apparatus of four suckers and tubercles (<?. app. fig. 48). 



The pen of the second specimen has been lost ; the type-sj)ecimen figured I have not 

 dissected. 



The most striking characteristic of this pretty little Ceplialopod consists in the distri- 

 bution of the phosphorescent organs in regular rows on the lower surface of the mantle, 

 funnel, head, and two ventral pairs of arms. The w'hole animal is of a creamy-white 

 colour, with a few browmish chromatophores at rare intervals, more especially on the 

 upper surface ; two of these, of exceptional size, are situated on the upper su.rface of 

 the head between the eyes (fig. 46). The eyes and buccal membrane are of a deep 

 purplish-brown colour. The phosphorescent organs already mentioned are arranged in 

 six longitudinal rows on the mantle, of which the two central rows are the widest ; also 

 on the funnel in six irregular rows (fig. 17). A row surrounds the lower half of each 

 eye, and three rows extend between these. The median row' bifurcates and runs up the 

 two ventral arms, together with the lateral rows. The ventro-lateral arms are provided 

 with one row of these organs, and a few are scattered along the edge of the mantle and 

 over the neck. The ventral arms are abnormally long and slender, and it seems probable 

 that the special organs already described at their tips are phosphorescent and used as 

 search-lights. 



Onychoteuthis Banksii, Leach. 



I refer provisionally one male specimen from Sandheads, and one large female 

 captured at a depth of 272 fathoms in the Bay of Bengal, to this species. 



2* 



