222 CLASS III. GASTEROPODA. ORDER VII. PECTINIBRANCHIATA. 
Pl. CCLX. Fig. 9. 
(A species of Turbinellus inserted inadvertently.) 
Pl. CCLX. Fig. 10. 
PuRPURA TESSELLATA, Sowerby, Genera of Shells, No. 42. 
Pl. CCLX. Fig. 11. 
Purpura arMiGcerA, Lamarck, Anim. sans vert., vol. vil. p. 257. Chem- 
nitz, Conch., vol. 11. pl. 187. f.1798 and 1799. 
Buccinum armigerum, Chemnitz. 
Pl. CCLX. Fig. 12. 
Purpura Mapreporarum, Sowerby, Genera of Shells, No. 42. 
Purpura monodonta, Quoy and Gaimard, Voyage de l’Astrolabe, Mol- 
lusques, pl. 37. f.9 toll. Kiener, Iconographie des Coquilles vi- 
vantes, pl. 17. f. 50. 
MONOCEROS, Lamarck. 
Testa ovata, spira interdum subelata, interdum depressa, anfractu ultimo 
inflato, inferné emarginato, in canalem brevissimum subproducto ; 
columella ampla, depresso-plana, plicis parvis interdum sed rard 
instructa ; apertura subsemilunari; labro plerumque crenato, pro- 
cessu dentiformi, acutissimo, elongato, ad inferiorem partem re- 
curvo, semper armato. Operculum corneum. 
The genus Monoceros was founded by Lamarck for the reception of 
certain of his Purpure, whose shells are characterized by their having a 
sharp, strongly-developed tooth protruding from the lower part of the 
external lip; and it was simultaneously introduced by De Montford 
under the title of Unicornus. If it were not that this dentiform process 
