MONOGRAPH 



01' 



THE ATLANTI DA E. 



25 



Species 10. Atlanta fusca Souleyet. 



1850. Atlanta brunnea l ) Gray. 

 1852. Atlanta fusca Souleyet. 



1904. Atlanta inclinata Vayssière (his fig. 91), non Souleyet. 

 (Plates 3 and 4, figs. 27—29). 



Dry shells: 



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

 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. helicinoides. 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). Around the umbilicus 5 — 7 spiral lines, 

 likewise uudulating, 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 auimal. 

 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 Museum, Vol. XXX. 



