290 BULLETIN OF THE BUREAU OF FISHERIES. 



DECAPODA. 



MYOPSIDA. 



The eyes are without free lids, although sometimes with a thickened fold forming a pseudo-lid; 

 their transparent covering membrane continuous with that of the head. The tentacles are usually 

 completely retractile. The oviduct is developed on the left side only. In some cases glandular lumi- 

 nous organs are present. 



Family SEPIOLIDjE Leach, 1817 (em.). 



Genus ROSSIA Owen, 1834. 



Rossia Owen, 1834, p. 93. 



Sepiolid decapods having the mantle free all round and (in addition to the fxmnel cartilages) articu- 

 lating with the head in the nuchal region by an ovate cartilage. Sessile arms short, with two to four 

 rows of spherical suckers. Tentacular arms almost entirely retractile. Both dorsal arms hectocotylized. 

 Gladius present but much reduced. 



A glandular luminous organ is known to be present in at least part of the species, situated just 

 behind the funnel. 



Type, Rossia palpebrosa Owen, 1834, a species of the Arctic region. 



Rossia pacifica Berry, 1911. (PI. xu-xlii; pi. xliii, fig. 1-4; pi. xuv, fig. i, 5.) 



Rossia pacifica Berry, 1911, p. 591. 



Body smooth, sepioliform, moderately large; the mantle full, somewhat flattened above and below; 

 rotinded behind; some specimens relatively short, others more slender. Fins large, subcordate, with a 

 free anterior lobe, their attachment more or less oblique to the general plane of the body. Mantle 

 margin free all round, articulating with the head by an elliptical cartilage in the nuchal region, and a 

 deep elongate groove with a prominent raised margin on either side of the base of the funnel ; the ridges 

 corresponding to the latter on the inner stirface of the mantle nearly straight and notably long and 

 heavy. 



Head very large, as wide as or wider than the body, and much flattened. Eyes large, the lower 

 lids free. Funnel short, conical, broad at the base, the extremity truncate; interior capacious, trans- 

 versely plicate, finely striate longitudinally; a delicate, rounded, flaplike valve on the dorsal wall 

 near the tip. Funnel organ prominent, comprising a large median liver-shaped pad and two elongate- 

 pyriform , flattened pads laterally placed on the interior surface of the ventral wall ; the latter broad and 

 curving inward at the base , the margins slightly raised, and the center apt to be occupied by a somewhat 

 sunken triangular area (pi. XLiv, fig. 5). 



Arms stout, thick, rather short, unequal, the order of length 3, 4=2, i; third pair joined with the 

 fourth by a well-developed web, functioning as a sheath for the tentacles; slight rudiments of an 

 umbrella also to be detected between all the other arms except the ventral pair; obscure carinations 



bras, larges, espac^es, celles de la derni^re moiti^ de ces organes, tr6spetites et excessivement rapproch^es. Couleur dans I'alcool, 

 d'un violet sombre sur les r(?gions supcrieures. jaiinAtre en dcssous. finement pointill^e de violet pale. Longueur totale du corps 

 y compris la tcte o".o3j. Largeur maxima o™.o2i. Longueur moyeenne des bras o^.ojs. 



"Cette forme pr^sente une certaine analogic avec I'Octopus punctatus Gabb., egalement de la basse Califomie. mais il en 

 diffferepar ime taille toujours petite, tandis que I'O.punctalus pent acquerirdefortes dimensions; Egalement aussi par la longueur 

 imiforme de tous les bras, par la petitesse exccptionnelle des yeux, la disposition de I'ombrelle et des ventouses, eniin par 

 I'aspect plus trapu du corps et sa coloration, dont il faut tenir compte pour la distinction des esp^ccs du genre Octopus." 



It is stated to come from Lower California and to live as a commensal organism between the valves of certain lamellibranch 

 mollusks inhabiting those coasts, very much after the manner of the common mussel-crab {Raphonolus), Should the truth ol 

 this be verified, the species and its unique habit are most remarkable. 



