﻿PTEROPODA.— Plate III. 



Thk depressed Hyaljea. Shell minute, white, sub- 

 trigonal ; compressed ; lateral processes projected 

 to the slit of the 'mouth ; aperture deeply semi- 

 lunar, simple ; outer lip produced, inner lip 

 slightly raised ; apex much produced, acu- 

 minated at the end, and hooked. 



D'Orbignt. Voy. Amer. Merid. PI. VII. f. 11-14. 



Hah. ? 



Genus ATLANTA, Lesuenr. 

 (Limacina, Cuvier.) 

 Tc-^lfi nantiliforiim, semicartilcgivom, spi rd plaimrhnJa, 

 nnfractibiis pariiiii cchitifi, iilti nm lenutter carivaio. 

 Shell nautilus-shaped, half iai-tii.iLciii"ns, spire flat- 

 circular; whorls partly hiddni, last with a thin 

 teel. 



Species 20. (Pig. a, b, Mus. Brit.) 

 Atlanta Peronii. Atl. testa compressd, temiisninK', 

 hyalind; anfractihus apparc.ntihus acute <iiigii- 

 latis ; uperturd anijustd ; margine externo aci<- 

 tissime angidatu ; carind lata, tenuissimd. 



Peron's Atlanta. Shell compressed, very thin, hya- 

 line ; whorls visible, sharply angular ; aperture 

 naiTow, its outer edge very acutely angular ; 

 keel broad, very thin. 



Lesueur. Les. et Blain. D'Orb. Amer. Merid. 



Hah. Atlantic. 



Species 21. (Pig. a, h, Mns. Brit.) 

 Atlanta (Oxygyrus) Kerandrenii. Atl. testa mni- 

 tricosd, memhrauaced ; aiifracilhus paucis, apica- 

 libus celatis, ulthno, extils, versus apicem late 

 carinato ; apertttrd lata, margine externo rotunda. 

 Kerandeen's Atlanta. Shell ventricose, membrana- 

 ceous ; whorls few, apical hidden, last towards 

 the aperture outside broadly keeled ; aperture 

 broad, outer margin rounded. 

 Rani:. Adams, Genera, p. 92. 



Hah. ? 



About 15 or 16 species of Atlanta and Oxygyrus 

 have been described, but we have not the opportunity 

 of presenting more than two representative species. 



