REPORT ON THE GASTEROPODA. 3 ( J 



Fissurisepta, ( Fissure a round hole at the tip, whole apex removed, shell glassy with minute white 



Seguenza. { tubercles, internal septum a straight slightly oblique lamina. 



Rimula, ( Fissure along cleft between top and front edge, apex persistent, sculpture reticulated, 



Defrance. \ no internal septum. 



Semperia, J Fissure a long cleft near the front edge, apex persistent, sculpture reticulated, no 



Crosse. \ internal septum. 



» 



This last genus is founded merely on the young shell of Emarginula fissura, Linn. = reticulata, 

 Sow., which very soon loses the distinctive feature referred to above, but often in maturity has the front 

 edges of the fissure very close together, and sometimes overlapping though separate. It is Emarginula 

 emendata, Sow., the Semperia paivana, Crosse. 



As regards the previous genus Rimula, it was created by Defrance for some Middle Eocene fossils 

 from the North of France. These unfortunately I did not see in the magnificent collection of the 

 Ecole des Mines at Paris, and the Jurassic Rimulas which I examined there are so choked with the hard 

 limestone matrix in which they are preserved, that the inside of the shell is invisible. Morris and 

 Lycett in their " Gasteropoda of the Great Oolite " (Pal. Soc. Lond., pp. 86 and 87) give no information 

 as to the interior of the species they describe. Pictet in his Palaeontologie (2d ed., vol. iii. p. 283), 

 while giving no help in his text, figures (see pi. lxviii. fig. 20) Rimula blainvillci, Defr., and shows the 

 interior certainly without any septum, which agrees exactly with Defrance's silence regarding any such 

 feature. Rimula is therefore a genus without a septum. That is how Adams understood it when 

 he classed under it his five little species from the Pacific. If, therefore, the presence of a septum 

 should be established in Defrance's type species, no choice would remain but either to suppress the 

 genus Rimula altogether, or, which would be better, to preserve the name and attribute the genus to 

 A. Adams. 



1. Puncturella clathrata, Jeffreys. 



Puncturella clathrata, J. Gwyn Jeffreys, "Lightning" and "Porcupine" MolL, Proc. Zool. Soc. 



Lond., Nov. 14, 1882, p. 676, pi. 1. fig. 11. 

 ,, plecta, Watson, Prelim. Report, pt. 16, Journ. Linn. Soc. Lond., vol. xvii. p. 34, sp. 6. 



Station 24. March 25, 1873. Lat. 18° 38' 30" N., long. 65° 5' 30" W. Off 

 Culebra Island, West Indies. 390 fathoms. Pteropod Ooze. 



Habitat. — North Atlantic. 



Shell. — Small, porcellanous, oblong, scarcely perceptibly broader in front ; its slopes 

 are conical and straight till close to the top, which projects backwards but little ; there 

 are strongish ribs and still stronger concentric threads ; the slit is short and broad. 

 Sculpture : There are about 35 strongish rounded riblets with feebler ones between, bring- 

 ing up the total number to 60 or 70 ; overlying these, and forming minute knots at the 

 crossings, are rather stronger, concentric, rounded threads, giving to the surface a wattled 

 appearance. Colour faintly brownish grey. Apex rather coarse, curled in, but very little 

 reverted or flattened ; there are just two whorls in all. Slit oblong, being short and 



