MURICID. 113 
Shell purpuriform ; inner lip flattened and depressed, but outer 
lip, when adult, thickened, inflected and toothed ; aperture wide. 
usmnLA, H. Adams. Founded on V. fusco-nigra, Pease, which 
differs from the typical Vexilla in the spire being acuminate, and 
the aperture somewhat contracted or narrowed. 
Pease (Am. Jour. Conch., iv, 115) adopts the subgenus, and 
adds to it Purpura leucostoma, Desh., and Planaxis cingulata, 
Gould. I very much doubt whether the group will stand, as the 
little specimen of Pease’s species before me is very suggestive 
of Pisania, and Deshayes’ species isa true Purpura, and evidently 
very closely allied to, and as I believe = P. columellaris. The 
opercula of Pease’s and Gould’s species are unfortunately unde- 
scribed. 
Ricrnuta, Lam. 
Etym.—Diminutive of ricinus, the (fruit of the) castor-oil 
plant. 
Syn.—Canrena, Link. Drupa, Bolt. Pentadactylus, Klein. 
Distr.—R. horrida, Lam. (xliv, 28,29). 30sp. India, China, 
Philippines, Australia, Pacific, Panama, Red Sea, Natal, West 
Indies, Brazil. 3 fossil sp. Miocene—; France. 
Shell ovate, solid; spire short, whorls tubercular or spinous ; 
aperture linear, narrow, contracted by callous projections, with 
a short, oblique, emarginate canal in front ; inner lip tubercularly 
wrinkled ; outer lip internally with plait-like teeth, often digitate. 
sistRUM, Montfort. (Morula, Montf.) Has usually a longer 
spire, the shell is smaller, more fusiform, the teeth within the 
outer lip not grouped, but single. This separation has its con- 
veniences: nevertheless the characters, as in so many other 
groups, only serve well for the recognition of some of the forms ; 
others must be arbitrarily placed. The dividing line between 
Sistrum and Engina, Latirus and some Pisanoid species is very 
difficult to trace. The group is essentially Polynesian in distri- 
bution, frequenting coral reefs. &. morus, Lam. (xliv, 30). 
Monoceros, Lam. 
Etym.—Monos, one, ceras, a horn. 
Syn.—Acanthina, Fischer. Rudolpha, Schum. Unicornus, 
Montf. 
Distr.—10 sp. California to Chili. Tertiary of Chili, M0. 
giganteum, Lesson (xlv, 41). MM. lugubre, Sowb. (xlv, 42). 
Shell ovate, last whorl large; spire rather elevated; aperture 
semilunar; inner lip wide and flattened; outer lip crenated, with 
a prominent tooth at the fore-part. 
PsEUDOLIVA, Swainson. 
Etym.—Resembling Oliva. 
Syn.—Sulcobuccinum, d’Orb. Gastridium, Gray. Buccinorbis, 
Conr. Pseudodactylus, Herm, 
