S. YOSHIWARA. 



I7ò 



3. A. owenii Ad. and Eve. 

 = A. comitato, Conrad. 

 = A. dispai' Conrad. 



found in the South Atlantic Ocean. 



4. A. kochiana Dunker, in the China Sea. 



5. A. nouryi Lorois, in the Equatorial Pacific, from the 

 Marquesas to the Peruvian coast. 



G. A. gondola Dillo. 



7. A. polita Conrad. 



8. A. bôttegeri Maltzan, in Japan. 



The only known fossil argonauts also helong to the same group, namely 

 A. sismondi Bell, and A. Mans Sol., both of which are found in the 

 Sub-Apennine Tertiary (Pliocene) of Piedmont. The latter species is 

 still living and world-wide in distribution. 



The second group has a broader keel and more numerous ribs 

 compared with the first ; and shows a somewhat triangular form of the 

 cross-section of the whorl. To this group belong : 



1. A. argo Linné. 



== A. pacifica Dali. 



= A. expansa Dali. 



= A. papyracea Conrad, 

 found in the Tropical Pacific, Indian and Atlantic Ocean, the Gulf of 

 California, the Mediterranean, and the Cape of Good Hope. 



2. A. grunneri Dunk. 



3. A. compressa Bl. 



4. A. frag His Park. 



The third and last group is represented by only one species 

 A. tuberculosa Linn., which is identical with A. nodosa Sol. and 

 A. oryzata Mensh. This species was found in Brazil, New Zealand, 

 Cape of Good Hope, New Jersey, North Island, Wellington, Chili, 

 Tasmania and South Australia. This species is very singular by having 

 tuberculated ribs, as in our specimens. However, these tubercles are 

 arranged in A. tuberculosa only in transverse rows, while in our form 



