Emarginula.] GASTROPODA. 99 



very rapidly increasing, the last large. Suture deep. Aperture large, 

 oval, the margins united by a strong callus. Outer lip sharp, simple. 

 Inner lip broadly reflexed. The slit is situate above the periphery, 

 short, not ridged or keeled, and strengthened by a fairly strong callus 

 on the inner side. 



Diameter, maj., 1*3 mm. ; height, 1 mm. (type). Diameter, ma j., 

 1-8 mm. ; height, 1*3 mm. (Snares specimen). 



Type in the British Museum. 



Hob. Lyttelton Harbour, on seaweeds, type (H. S.) ; Lyall Bay, 

 near Wellington ; Snares, in 50 fathoms (Captain Bollons). 



Remarks. There is no operculum, and the radula approaches that 

 of Emarginula. 



Genus 2. EMARGINULA, Lamarck, 1801. 



Emarginula, Lamarck, Syst. A.s.V., 1801, 69. Type : Patella fissura, L. 

 Emarginula, Lamarck : Fischer, Man. de Conch., 858 ; Man. Conch. (1), 

 xii, 202, 248. Semperia, Crosse, J. de Conch., 1867, 74. 



Animal having the snout large, tentacles long, eyes on distinct 

 peduncles ; mantle forming a tubular process extending beyond the 

 anterior anal slit in the shell ; having epipodial papillae, and the foot 

 oval. Central tooth of radula large, quadrangular ; the inner 4 lateral 

 teeth long and narrow ; the fifth large, bicuspid, its upper part bent 

 horizontally ; uncini numerous. 



Shell oval, obliquely conical, the recurved apex directed backward ; 

 front slope with a deep incision in the margin. A distinct anal fas- 

 ciole extends upward from the fissure, sculptured differently from 

 the other ribs of the surface ; surface latticed ; no septum or deck 

 inside. 



From the Carboniferous to Recent ; many species are known from 

 the Tertiary. The Recent species of Emarginula s.s. number about 

 sixty, and are recorded from the Mediterranean, the Atlantic, the 

 Gulf of Mexico, and the Indo-Pacific. They live from the upper 

 laminarian to the coralline zone. 



Vernacular Name. Slit-limpet. 



1. Emarginula striatula, Quoy and Gaimard, 1834. Plate 8, fig. 5. 



Emarginula striatula, Q. & G., Voy. Astrol., Zool., iii, 1834, 332, pi. 68, 

 f. 21, 22 ; Man. Conch. (1), xii, 259, pi. 64, f. 2. 



Shell ovate-conic, fragile and thin, apex oblique, recurved. Sculp- 

 ture : Radiating ribs close together, granulate ; spiral ridges of growth 

 prominent, irregular, producing with the -ribs subcancellation. Colour 

 greyish or greenish-white. Margin crenulated. Slit deeply excavated. 

 Intericr white to greenish. 



4* 



