418 DR. A. H. COOKE OX THE 



consist of a single curved blade, as in Oliva, Murex, Trophon, 

 Thais, and the allied groups. As a rule the base is narrower, 

 and the blade thinner than in these genera. The rhachidian 

 tooth is bow-shaped, frainewoi'k narrow, pointed at the ends, set 

 either with many small sharp cusps, wdiich cover nearly the whole 

 of the upper mai-gin, or with three only, closely grouped together 

 in the centre. The whole radula is as a rule extremely small. 



Group (1). Rhachidian set with many small sharp cusps, tips 

 of framework curving slightly up, and pointed at the ends, which 

 are bare of cusps. 



1. V. alaiida Quoy. Mauritius. Framework of rhachidian 

 moderately curved, set with 16-17 minute denticles, diminishing 

 outwardly, ends bare, scarcely turned up: laterals simply hooked, 

 not deeply curved. 



2. r. «renosi«)i Lam. Philippines. Framework of rZtacAzc^mu 

 deeply arched in bow shape, set with 20-22 sharp denticles, not 

 deeply set, which diminish gi'adually in size to mere points, and 

 finally leave the ends bare, central denticle the largest; ends 

 sharply turned up: laterals simple hooks, not deepl}'- curved. 



3. V. cruentatum Chem, Philippines. Rhachidian not very 

 deeply Avaved ; denticles 19-20, closely packed and narrow, 

 central the largest ; a small blank space at the ends of the frame- 

 work : laterals with very narrow blades, slightly hooked at the 

 tip., 



Text-figure 17. 



Lateral and rliacliidiau tooth of Vexillum e.rasperatum Gmel. 



4. V.exas})eratumQme\. Maiuitius. ^A(xcAiVZi««. deeply curved 

 in bow shape, ends of framework narrow and bare ; set with 

 15-16 sharp narrow cusps, equal in size, except those at the 

 extreme ends, which become suddenly smaller : laterals long and 

 narrow, hooked at tip. 



5. V. h/ratum Lam. Mauritius. Framework of rhachidian 

 deeply bow-shaped, ends scarcely turning up, tips bare ; denticles 

 13-15, shaip, thin, rather distant from one another, central 

 rather the largest : laterals long, narrow, very sharply pointed. 



6. V. nodosum Swains. Hilo. Rhachidian bow-curved, but 

 not ver}^ strongly, tips bare ; denticles 7-8, sharp, triangular, 

 close together : blade of laterals much curved. 



7. V. iasmanicum T.-Woods. N. Tasmania. Kadula very 

 small ; rhachidian bow-shaped, well curved in centre, tips of 

 framework bare and turned upward; denticles 10-11, sharp, 

 close together, equal-sized, but diminishing towards the ends : 

 laterals nai-row-ldnded, curving sharply in the centre. 



8. V. teresice T.-Woods. Tasmania. Framework of rhachidian 



