MOLLUSCA. 



x^ 



PART III. EUPTEROPODA (PTEROPODA THECOSOMATA) 

 AND PTEROTA (PTEROPODA GYMNOSOMATA.)* 



BY ANNE L. MASSY. 



WITH NINE FIGURES IN THE- TEXT. 



r UJE 

 I. Introduction ..... . . 20:; 



II. List of Species taken by the "Terra Nova" Expedition 205 



III. List of Stations at which Pteropods were obtained 200 



IV. Descriptions of Species . . . 208 



V. List of References . 227 



Index . 229 



I. INTRODUCTION. 



THIS collection although not containing any species new to science is nevertheless of 

 great interest, especially i'rom a geographical point of view. 



Yayssiere (1915, pp. 4-5) has shown that the two groups of Pteropoda, those with 

 and without shells, are in reality not closely related to one another, and. consequently, 

 lie suggests that the names selected liy Boas for the t\v<> Croups shall he revived, naiueh 

 tliat of Euptcropoda for the first group and 1'terota tor the naked species. These names 

 have the advantage of separating the two groups whilst indicating always the existence 

 of the must apparent external character, the fins. 



The seventeen species of Kupteropoda in this report comprise five in-ncra and two 

 suhgeiiera and consist of some thirty thousand individuals. The I'terota numher three 

 species heloniiing to as many genera and included under three thousand four hundred 

 individuals. The area explored hy the "Terra Nova' included sixty-six hauls in the 

 Atlantic, at or near the surface in the region from the Hay of Biscav to off l!io de 

 Janeiro, and representatives of hoth groups were taken in alxuit one third of the hauls. 



MS. received December 15, 1919 (S. F. H.). 



Vol.. II. "2 I 



