78 



43. Janellii, Kiener. 



44. kiosquiformis, Buclos. 



45. lapillus, Lam. 



46. lineata, id. 



47. luteostoma, Desk. 



48. Madreporarum, Sow. 



49. mancinella, Lam. 



50. melones, D/iclos. 



51. muricina. Be Blainv. 



52. inusiva, Kiener. 



53. Neritoidea, Des/«. 



54. nux, Reeve. 



55. patula, Lam. 



56. persica, /^/w. 



57. pica, Be. Blainv, 



58. planospira, Lam. 



59. pupillata, #eei?£. 



60. Qiioyi, id. 



61. Eudolphi, Zow. 



62. rustica, id. 



63. sacellum (Murex), Ck. 



64. Scalariformis, iara. 



65. scobina, Quay. 



66. septentrionalis, Reeve. 



67. speciosa, Valenc. 



68. spiralis, Reeve. 



69. squamosa, Xow. 



70. squamulosa, Reeve. 



71. succincta, Zffim. 



72. textilosa, z'c?. 



73. thiarella, id. 



74. trigona, Reeve. 



75. trochlea, Za»z. 



76. tiimulosa, Reeve. 



77. undata, Zaw. 



78. unifascialis Lam. 



79. violacea, Kiener. 



80. xanthostoma, i?m/. 



Figure. 



Purpura aperta. Plate. 6. Fig. 30. Shell showing its depressed spire, 

 dilated aperture, and flattened columella. 



Genus 20. COLUMBELLA, Lamarck. 



Animal ; disc elongated and narrow, truncated and a little dilated 

 in front, hind extremity furnished with a small horn?/ oper- 

 culum, head small, flattened, triangular, prolonged into two 

 conical cylindrical tentacles, pedunculated to about a third of 

 their extent, at the summit of which portion are the eyes ; trunk 

 rather long. 



Shell ; small, ovately oblong or triangular, sometimes fusiform, 

 columella arched and denticulated, rarely smooth ; outer lip 

 thickened, swollen^ gibbous and most frequently denticulated in 

 the middle. 



The genus Columbella includes a very numerous series whose shells are 

 uniformly small, and distinguished by a greater or less number of plait-like 

 denticles on the lip and columella after the manner of Bicinula. Prom the 

 circumstance of Lamarck having confounded a few of the small Mitres 

 with the Columbella, he was induced to refer the genus to the family Colu- 

 ■mellata, assuming the existence of a plaited columella ; the plaits by which 

 the genera of that family are characterized are, however, of very different 

 structure, from the protuberances which are here designated plait-like 

 denticles ; the first being developed on the columella throughout its entire 

 growth so as to form a continuous winding of spiral plaits around the 

 columella axis, whilst the last are merely developed along the inner side of 

 the columella, on arriving at maturity. 



