416 PROCEEDINGS OF THE ACADEMY OF [July, 



under the high power seem to be smooth, but the material examined 

 is imperfectly stained. 



Color in life unknown; in alcohol a pale brown, suffused here 

 and there with blackish-purple. Chromatophores numerous, ap- 

 pearing as dark dots. As in the other species of the genus, the 

 ventral surface of the mantle is marked by a large shield-shaped 

 patch, over which the chromatophores are exceedingly fine, numerous, 

 and evenly distributed; the patch is bordered by a rather indistinct 

 slaty-blue margin. 



Beak and radula not examined. Gladius absent. 



Type.— Cat. No. 2.027 (Invertebrate Series) of the Stanford 

 University collections; a male. The type is unique. [S. S. B. 

 No. 32.] 



Type Locality. — Suruga Bay, Japan. 



Measurements. — The chief measurements of the type are as follows: 



mm. 



Total length exclusive of tentacles 38.5 



Medio-dorsal length of mantle 17 



Medio-ventral length of mantle 20 



Width of body 13 



Width across fins 24 



Length of fin, total 13 



Length of fin at plane of attachment 9 



Width of nuchal commissure 4.5 



Width of head 14 



Length of head 9 



Length of dorsal arm 1 1 



Length of second arm 12 



Length of third arm 10.5 



Length of ventral arm (measured from inner base) 10 



Length of tentacle 20 



S. nipponensis appears to be very different from either of the 

 only two species of the genus heretofore described, although sharing 

 with them the curious combination of characters upon which the 

 group was founded. The generic type — S. leucoptera Verrill, from 

 the North Atlantic — differs in the more complete webbing of the 

 arms, their relative shortness, the more anterior position of the fins, 

 hectocotylization (though affecting the same arms), and other 

 details. It is also stated to have the eyelids free all round, but from 

 the appearance of the present specimen this should possibly be 

 regarded as a physiological condition, rather than a permanent 

 feature as in the cegopsid decapods. 



The other Pacific form— S. iris Berry, from the Hawaiian Islands— 

 totally different aspect and stands quite alone in the relative 



