CEPHALOPODS OF WESTERN NORTH AMERICA. 275 



Family ARGONAUTID/E Cantraine, 1840. 



OcYTHOiD^ Gray, 1849. 

 Genus ARGONAUTA Linne, 1758. 



Arffiynauta Linne, 1758, p. 708. 



Ocylhoe Gray, 1849, p. 30 (not of Rafinesque). 



Pelagic octopods of moderate size, the male much smaller than the female and with the hectoco- 

 tylus involving the entire third arm on the left side, which is developed in an oval sac, much enlarged, 

 and separable. In the female the tips of the dorsal arms are greatly expanded, wing like, and their 

 function is to secrete the large fragile external "shell " or egg case. Mantle connectives well developed. 

 Aquiferous pores present on the head. 



No other group at all approaches Argonauta in its assemblage of utterly distinctive characters, the 

 nearest being the genera Ocylhoe and Tremoctopus, which are not known to be represented in our waters. 

 The genus comprises the familiar and beautiful "argonauts" found in all warm seas. The delicate egg 

 case is the greatly prized shell popularly known as the "paper nautilus. " 



Type, A. Argo Linn6, 1758, a common Mediterranean and Atlantic species. 



Argonauta pacifica Dall, 1872. 



^ArQtynauta Argo Reeve, i86r, pi. m, fig. 2d. 

 Argonauta Argo Carpenter. 1864, p. 613,664 (merely listed). 

 Argonauta Argo Steams, 1867, p. 345 (merely listed). 

 Argonauta pacifica Dall, 1869, p. 237 (no description). 



Dall, 1872, p. 95. 

 Argonauta Argo (pars) Tryon. 1879, p. 139, pi. 49, fig. 120 (? fig. 121, after Reeve). 

 Argonauta pacificaHoy\*^, 1S86, p. 5 (no description). 



Hoyle, 1886a, p. 213 (9). (no description). 

 Argonauta argo Yates (err. typ.), 1889, p. 178 (merely listed). 

 Argonauta Argo Yates, 1890, p. 45 (merely listed). 

 Argonauta pacifica Williamson, 1892, p. 217 (merely listed). 



Keep, 1904, p. 271.350 (no description). 

 Argonauta pacifica Dall, 1908, p. 225. 

 Argonauta argo pacifica Dall, op. cit., p. 226.228. 

 Argonauta pacifica Dall, 1909, p. 193 (merely listed). 



Keep, 1910, p. 296 (no description). 



The essence of the original diagnosis is as follows, comparison being made with the Mediterranean 

 A. argo: 



" The animal of the Califomian species is orange, witli a .sprinkling of fine purple dots, more crowded 

 and larger on the back. The proportions of Uie arms are different from those of the .1. argo. The first 

 pair are a little the longest, tlie second next in length, while in A. argo tliey are tlie shortest; the tliird 

 pair are the shortest and the fourth equal to the third. Tlie web extends along only one-half of tlie 

 fourth pair, and is proportionately smaller than in A. argo; the siphon is sliorter with a blunt elbow. 

 The dentition also differs. The central tooth is proportionately larger, much broader, and slightly 

 convex in tlie middle line in front. The first lateral is smaller and the inner comer produced into a 

 denticle. The second lateral is proportionately larger and the third narrower and smaller than in A. 

 argo. The shell is more ventricose, and tlie arrangement of the sculpture and tubercles is different from 

 tliat of the Mediterranean species." (Dall, American Journal of Conchologj', vol. vii, p. 96, 1872.") 



Distribution: Monterey, California (Dall); Santa Rosa Island, California (Yates); Santa Cruz Island, 

 California (Cooper, Steams); Santa Catalina Island, California;'' San Pedro, California (Tryon); Gulf 

 of California (Dall); Gulf of Panama (Albatross, Dall); near tlie Galapagos Islands (Albatross, Dall). 



a For a popular account sec the article entitled " A tame nautilus," by Charles F. Holder in the Scientific American for October 

 16, 1909. 



