367 



base very difficult to distinguish. Laterals 18, with a very 

 long large cusp, on a short thick base : fig. 55 is a side view. 

 The 21 marginals gradually diminish till extremely small. 

 They are tricuspid, one cusp very large and blunt, and one 

 very small on each side near its base. The basal plates of the 

 marginals are small and indistinct. S. tristensis, Sowerby 

 (fig. 278, Fischer's Man. de Conch.), shows a secondary small 

 cusp on the laterals. 



Siphonaria baconi, Reeve. 

 PI. xx., No. 4, x 450. 



Dental formula ' ' 88 °' . Radula broad, yellowish. Cen- 

 tral tooth with one cusp on a long narrow bifurcated base. 

 Laterals 13, with one very large blunt cusp on a small base. 

 It is rather difficult to determine where the marginals begin, 

 but there are about 19, tricuspid with one large median cusp 

 and two small ones on a very diminutive base. They gradually 

 decrease in size to a small rectangular plate with a tiny 

 abutment on the lower side. 



Gadinia angasi, Dall. 

 PI. xx., No. 6, x 1000. 

 Dental formula 300 i ^ o - 30 . Radula delicate, teeth extremely 

 small. Marginals and laterals are so alike that they have been 

 grouped together as 30 marginals. Central tooth with one 

 dark, pointed cusp on a slightly broader base. Marginals 

 bicuspid, with one very long sharp cusp and a minute one, 

 fixed to a small basal plate (in profile in fig. 6b ). The teeth 

 gradually lessen in size, and become shapeless. The large 

 tusk-like apearance of the big cusp of the marginals is a 

 striking feature. 



EXPLANATION OF PLATES. 



Plate XIX. 



1. Radula of Trophon flindersi, Ads. and Ang. 



2. ,, Fasciolaria fusiformis, Valenciennes. 



3. ,, Megatebennus concatenatus, Crosse and Fischer. 



4. „ Emarginula Candida, H. Adams. 



5a. ,, Phasianella australis, Gmelin; also 5b. 



6 ,, Phasianotrochus irisodontes, Quoy and Gaimard. 



7. ,, Fasciolaria australasia, Perry. 



8. ,, Cypraia angustata, var. declivis, Sowerby. 



9. ,, Lucapinella oblonga, Menke. 

 10. ,, Emarginula dilecta, A. Adams. 



