Habitat: — Tvvo shells of ^\". schepmani were brought up in a deep-sea trawl at St. 221 

 (6° 24' S., i24°39'E., 2798 mètres). 



Remarks : — The very peculiar donaciform appearance of the shell and sculpture are 

 characteristic of this species. 



3. Neilonella weberi sp. nov. (Plate VIII, figs. 5 — 8). 



The following is a description of this new species : — Shell of small size, thick, rounded 

 ovate, subequilateral, slightly oblique, very tumid; ventral margin very arcuate; umbones prominent, 

 tumid, obtuse curved inwards and backwards ; sculpture consisting-of very regular, low, concentric 

 ridges, equally developed ail over ; hinge-plate moderately strong, anterior séries ofteeth somewhat 

 shorter than posterior. Shell of a pale yellow colour, nacre white. 



Measurements of Holotype : — Length 4.3 mm., height 3.8 mm., diameter 3 mm. 



Habitat : — The unique partly damaged Holotype of Neilonella ivebcri was brought up 

 in a deep-sea trawl at St. 271 (5°46'.7S., i34°o'E., 1788 mètres). 



4. Neilonella delicatula sp. nov. (Plate I, figs. 52, 53). 



The following is a description of this new species: - — Shell of small size, very thin, 

 délicate, rounded ovate; subequilateral; moderately tumid; regularly curved both anteriorly and 

 posteriorly; ventral margin greatly arched; umbones moderately prominent, acute, curved inwards 

 and backwards; shell surface almost smooth, hinge-plate moderately developed; 8 minute teeth 

 in anterior, 10 in posterior séries. Shell of a yellowish colour, nacre white. 



Measurements of Holotype: — Length 4 mm., height 3.2 mm., diameter 2.8 mm. 



Habitat: ■ — The unique Holotype brought up in a deep-sea trawl at St. 211 (5° 40'. 7 S., 

 i20°45'.5E., II 58 mètres). 



Remarks: — The shell of this species is very thin and fragile. In form A^. delicahila 

 resembles N. wedej'i Prashad, but the sculpture and the hinge of the two are very différent. 



