NON-MARINE MOLLUSCS OF SURINAM. 33 
lamarckiana atra 
last whorl a little ascending | not ascending 
at the peristome | 
| 
| 
| 
axis of peristome | very oblique slightly oblique 
outer and basal lip thickened sharp 
callus on inner lip | thick thin 
between base of pe- gutter no gutter 
ristome and co- | 
lumella 
I feel obliged however to admit that some specimens, 
ranged by me under D. lamarckiana, seem to be inter- 
mediate forms between both species. Perhaps a sexual 
difference might be expressed by the shape of the shell. 
Until a great number of specimens from all parts of the 
Guyana’s will be collected, I will not impute too much 
importance to the fact that most of the D. lamarckiana 
are recorded from the western parts, most of the D. atra 
from the eastern parts of Guyana. 
*81. DoRYssA DEVIANS Brot. 
Doryssa devians, Brot, Syst. Conch. Cab., Ed. nov., Band TI, 
Abt. 24, 1874, p. 352, T. 35, f. 10, 10 a—e. 
Lawa. Gonini-Expeditie. 
Lenabari. Gonini-Expeditie. 
Brot, 1874, p. 352. Upper-Surinam River, Marowijne. 
Schepman, 1887, p. 155. Marowijne (subfossil). 
Martin, 1888, p. 68. Surinam River. 
The Lenabari-specimens are agreeing with the inter- 
mediate form, Brot’s fig. 10a; the Lawa-specimens, that 
are not or very faintly shouldered at the last whorl, are 
more like the var. 6 of Brot, fig. 105. Most of the speci- 
mens have the spire strongly decollated and eroded. Ex- 
ceptionnally one -Lawa-specimen is lacking only a few 
whorls at the apex; its length is 80 m.M. 
* 82. DoRYssA GRACILIS nov. sp. (fig. 10). 
Shell oblong, turrite, solid, dark greenish brown, with 
olivaceous spots visible at the base. Apex decollated, 
remaining whorls 6, slowly increasing, with spiral wrinkles, 
Notes from the Leyden Museum, Vol. XXXVI. 
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