﻿MONOGRAPH OF THE ATLANTIDAE. 



25 



Species 10. Atlanta fusca Souleyet. 



1850. Atlanta brunnea Gray. 

 1852. Atlanta fusca Souleyet. 



1904. Atlanta indinata Yayssiere (his fig. 91), non Souleyet. 

 (Plates 3 and 4, figs. 27-29). 



Dry shells: 



Indian Ocean, purchased 1907, 5 sp., Sowerby and Tulton. 

 Animals : 



Red Sea, April '06, 1 sp., Buitendijk. 



Indian Ocean, September '06, 1 sp., „ 



„ July '07, 1 sp., „ 



At first sight this species may be confounded with A. 

 inflata or A. lielicmoides. It is, however, distinguished by 

 a whole series of characters : 1°. by the spire forming a 

 short cone with a more pointed apex (fig. 28), 2°. by the 

 very broad keel, extending to inner and outer lip, and so 

 encircling the whole shell, 3°. by the dark horn-colour, 

 also on the keel, about the same as in the foregoing 

 species, especially on the spire, and 4°. by a very characteristic 

 sculpture : 2 — 3 spiral lines on the apical whorls, which 

 number increases to 12 — 14 on the second half of the 

 penultimate whorl (fig. 27), where these lines are slightly 

 undulated (fig. 28). x^round the umbilicus 5 — 7 spiral lines, 

 likewise undulating, are distinctly visible. In no other species 

 of Atlanta the spiral sculpture is so strongly accentuated, 

 it occurs even in the largest shells of 2 — 2,5 mm., and 

 may persist throughout the whole life of the animal. 

 Transverse striae of growth are also very distinct on the 

 last whorl, and here another remarkable feature may be 

 mentioned : numerous rows of tiny points, parallel 



]) This name has been given by Gray, translating //Atlante brune", under which 

 title the species is designated by Souleyet in the Atlas of the « Voyage de la 

 Bonite"", which appeared already in 1842. 



Notes from the Leyden JMuseiim, Vol. XXX. 



