64. nodiferus, Lam. 



65. obscurus, Reeve. 



66. olearium, Desk. 



67. pagodas, Reeve. 



68. Pfeifferianus, id. 



69. pictus, id. 



70. pilearis, Lam. 



71. pygmseus, Pfeiffer. 



72. pyrum, Za?w. 



73. Quoyi, ife«?e. 



74. Banelloides, z'rf. 



75. reticulatus, Blain. 



76. retusus, Zaw. 



77. ridens, Reeve. 



98 



78. nubecula, Lam. 



79. rudis, ZVof?. 



80. sarcostoma, Reeve. 



81. Sauliae, &<?. 



82. scabra, A7»#. 



83. Scalariformis, Brod. 



84. scrobiculator, Za;«. 



85. sculp tills, id. 



86. Sinensis, id. 



87. sipbonatus, irf. 



88. Soverbii, id. . 



89. Spengleri, Lam. 



90. subdistortus, z^. 



91. tessellatus, Reeve. 



92. Thersites, i^. 



93. triginus, Brod. 



94. tortuosus, Reeve. 



95. Tranquebaricus, Za?». 



96. trilineatus, Reeve. 



97. tripus, Za»«. 



98. truncatus, Hinds. 



99. tuberosus, Zam. 



100. variegatus, id. 



101. verrucosus, Reeve. 



102. vespaceus, Zam. 



103. vestitus, Hinds. 



Figures. 



Triton tuberosus. PL G. — Shell with animal, showing its short disc, 

 truncated head, pointed tentacles and ocellated painting. — From the 

 * Voyage de I' Astrolabe.' 



Triton tigrinus. PI. 9. Fig. 43. Shell (diminished two-thirds), showing 

 a strong varix on the left side. — From Mr. Cuming's collection. 



Genus 2. RANELLA, Lamarck. 



Animal ; similar to that of Triton. 



Shell ; ovate or oblong-ovate, with the spire more or less acumi- 

 nated ; varices mostly oblique, deposited one on every half- 

 whorl, forming a longitudinal row on each side ; canal some- 

 times very short, sometimes rather long ; aperture ovate, gene- 

 rally canaliculated at both ends. 



The genus Ranella was founded by Lamarck upon a peculiarity mani- 

 fested in the arrangement of the varices, by which the shell acquires a de- 

 pressed two-edged structure. The animal varies in no respect from Triton, 

 except in the mode in which it forms its shell ; the varices or marginal 

 borders, resulting from a periodical function of the mantle, are deposited 

 exactly one on every half-volution, ranging therefore on either side of the 

 shell, like a continuous wing-like appendage from the apex to nearly the base. 



Having treated of the mode in which this function is exercised, under 

 the head of Triton, it may here be noticed that De Blainville assumed them 

 to indicate periods of gestation ; but M. Deshayes observes, in reply to this, 

 that, " the varices being deposited from the earliest formation of the shell, it 

 is quite unnatural to suppose, that the animal has the faculty of employing 



