CEPHALOPODS OF WESTERN NORTH AMERICA. 

 Specimens of Rossia pacifica — Continued. 



293 



It is strange that I can find no reference in the literature to any Pacific Rossia, especially since 

 R. pacifica appears to be a most abundant species and has long been known to workers in this region, 

 even appearing as "Rossia sp." in a few local lists and manuscripts (if I am correct in assuming that the 

 animals so referred to are the same as those here described). At first some doubt was felt as to the proper 

 status of the present form, but extended study of a very large series of individuals has convinced me 

 that it is distinct from any of the species previously described. The characters relied upon are small 

 and may seem trivial, but appear to be constant even in specimensfrom widely distant localities, so that 

 no other view seems feasible. The genus is a remarkably homogeneous one, and though a largenumber 

 of species have been described, many of them differ from one another only relatively and in slight 

 degree. The true value of many of them is certainly not yet established beyond all doubt. Our species 

 appears to be nearest to R. macrosoma (Delle Chiaje) d'Orbigny, originally described from the Mediter- 

 ranean, but there are numerous small discrepancies, notably in the structtire of the arms in the male. 

 I have not had the opportunity to examine actual specimens of the European species, but in the excel- 

 lent figures given by Jatta (1896, pi. 15, fig. 6) only the outer two rows of suckers on the lateral arm 

 suffer enlargement, whereas in R. pacifica all arc usually subequal. The hectocotylization is similar 

 to that figtircd for R. macrosoma, but differs slightly in detail. Fiuthermore, the tentacular suckers do 

 not seem to be so thickly distributed in R. pacifiica, especially at the base of tlie club. 



R. pacifica is one of the most abundant of the littoral West American cephalopods, and it is remark- 

 able that it has escaped a diagnosis so long. The specimens taken show a wide range from southern 

 Alaska to San Diego, and their abimdance at both extremes indicates that they will eventually be foiuid 

 to extend far outside of these limits. 



There is considerable variation in the shape of the body, the females as a rule being rather shorter 

 and perhaps more pltimp than the males; but when sex is taken into consideration the measurements 

 in the table (from specimens selected quite at random) are seen to be surprisingly constant, with the 

 exception of the last three columns. Tlie latter were taken from quite deep water in the vicinity of 

 San Diego, California. Noneof the specimcnsobserved from tliis region agree entirely with the type, and 

 it is not impossible that theyare incorrectly referred to this species. Thcydiffcr in being uniformly 

 much smaller, in every way more slender and delicate, the fins relatively larger, and the suckers of the 

 sessile arms borne predominantly in two rows, only here and tliere (notably in the case of the hcctoco- 

 tylized arms) assuming the four-rowed condition. The constant character of tliese divergences may 

 well be recognized to advantage, so that the subspecific name diegensis is here proposed. Should 

 further material from the wide unexplored area intervening between Monterey Bay and San Diego 

 fail to show intergrading forms it is likely that the southern specimens represent a newspecies. (PI. xun, 

 figs. 2-6; pi. xun, fig. I.) 



A specimen from Albatross station 4377 is peculiar in that tlie body is extremely full and short, the 

 head relatively larger than usual; the suckers, irregular in size and in two rows on all tlie arms, show 

 that this too is only a slightly variant diegensis. It should be stated that the foiu'-rowed state seems at 

 best but a secondary one and more apparent than real. 



