REPOET ON THE CEPHALOPODA. 



109 



Japetella prismatica^ Hoyle (PI. IX. figs. 1, 2). 



1885. Japetella prismatiea, Hoyle, Diagnoses I., p. 231. 



1885. „ „ Hoyle, Narr. ChaU. Exp., vol. i. p. 271, fig. 107. 



1885. „ „ Hoyle, Prelim. Eep. I., p. 107, woodcut. 



Habitat. — Station 126, off the Kio San Francisco, Brazil, September 12, 1873; 

 lat. 10° 46' S., long. 36° 8' W.; 770 fathoms; red mud. One specimen, probably $ . 



The Body is of gelatinous consistency and semitransparent ; it is somewhat 

 longer than broad, flat on the dorsum, and with the median ventral region raised into 

 a prominent ridge, which gives the bodj^ a prismatic form (fig. 1). The mantle- 

 opening appears to have been wide, and to have terminated behind the eyes ; but as the 

 integument has been torn away from the head dorsally, it is impossible to be certain of 

 this. The siphon extends almost to the margin of the umbrella, and is but slightly 

 conical, with a broad truncated extremity ; internally it is provided with a distinct valve. 



The Head is about as broad as the body ; the eyes are rounded, and prominent 

 laterally, the spherical lens protruding from the middle of each. 



The Arms are unequal, the third pair being the largest, one quarter longer than the 

 body, and about one-third longer than the fourth, which are slightly longer than the 

 second, and these than the first, so that the order of length is 3, 4, 2, 1. The arms are 

 stout, and taper gradually to blunt points. The umbrella extends about halfway up 

 the dorsal arms and one-fourth up the ventral arms, its extent being intermediate 

 between these extremes in the case of the other arms. The suckers are round and 

 prominent, and in many cases show a double margin, due to a thin fold of skin 

 surrounding the thickened edge of the sucker ; they commence one sucker's breadth 

 from the oral margin, and become gradually larger and wider apart as far as the 

 middle of the arm, where they are one sucker's breadth apart, after which they are 

 smaller and closer, and towards the extremity stand in contact. There is no trace of a 

 hectocotylus. 



TJie Surface of the body appears to have been perfectly smooth ; it is covered with 

 torn remains of epithelium, but there are neither warts nor cirri. 



TJie Colour is a pale yellowish-grey, and there are numerous reddish -brown 

 chromatophores. 



Dimensions. 



Length, total, ....... 



70 mm. 



End of body to mantle-margin, ..... 



27 „ 



End of body to eye, ...,,.. 



33 „ 



Breadth of body, ...... 



22 „ 



Breadth of head, ....... 



20 „ 



Eye to edge of umbrella, ...... 



19 „ 



Diameter of largest sucker, ..... 



1-5 „ 



1 So called from the form of the body. 





