L I V A . 



Genus OLIVA, Bncguiire. 



Te.iia obloiiya, Irsvis, mhcylindracea, had emarginata, spird 

 plenmqice breviuacidd, suttiris pet'uliariter canalicu- 

 lafis, columelld pUcatd, plicis obsciiris, variis, sape 

 plamdatis e( callosis. Apertura elongata, angmta, 

 interdnm mhpatula. 



Shell oblong, smooth, somewhat cylindrical, cmarginated 

 at the base, spke generally rathe]- short, with the 

 sutures peculiarly canaliculated, columella plaited, 

 plaits obscure, variable, often flattened and callous. 

 Aperture elongate, narrow, sometimes rather wide. 



The Olives ai-e a verj' distinct group of moUusks, par- 

 taking of the characters of Cypi-aa and Ancillaria, but 

 more of the latter than of the foimer genus. The shell, 

 as may be gathered from its enamelled interior, is en- 

 veloped by certain parts of the animal, and like that of 

 Oyprcea is generally composed of two or more layers of 

 different pattern. This variety of colouring is not, how- 

 ever, shown at different stages of the shell's growth as 

 in Cypraa : it is only to be discovered by removing the 

 outer coat with acid. Hence it may be inferred that the 

 different coatings are deposited simultaneously dui'ing the 

 formation of the shell, whilst the mantle is fur-led, so to 

 speak, over the edge of the lip, and held in a state of 

 tension by a cord which passes into the narrow sutural 

 channel of the spu-e. Specimens of 0. gihhosa and Bra- 

 silieusis are frequently sold by dealers with the outer 

 coating removed to show the pattern beneath, in order to 

 give them the appearance of other species. 



The genus Olivet has generally been regarded as one 

 of which the species are extremely diSicult to determine. 

 They have not proved so on examination. Species, bke 

 0. reticularis, for example, which difl'cr very much in 

 form, are distinguished by a marked peculiarity of pat- 

 tern ; and others, Kke 0. injiata, which present an almost 

 endless variety of pattern, are characterized by some pecu- 

 liarity of form. In 0. ispidiila, which varies in an ex- 

 traordinary degree both in form and pattern, the shell is 

 constantly distinguished by the same particular colour in 

 the interior, and there are several species, like 0. crueiita, 

 whose varieties are but so many different phases of the 

 same idea of pattern. 



The principal localities of this genus arc Mauritius and 

 the Philippine Islands in the eastern hemisphere, and 

 Central America in the western. Out of a hundred species 



j described in the following monograph, the habitats of 

 I about seventy are determined. — Mauritius, Ceylon, the 

 Molucca and Pliilippine Islands yield about twenty-five 

 species, including the large and richly-coloured 0. treinu- 

 lina, erythrostoma, Objmpiadina, nobilis, textiUna, &c. ; and 

 Central America about thirty species. Fifteen of these are 

 from Panama, Guayaquil, Nicaragua, Mexico, &c., among 

 which are the giant 0. porphyria, and the beautiful 0. an- 

 gukita, splendidula, polpasta, testacea, &c., and fifteen from 

 the West Indies, all of which are small, with the single 

 exception O.fmiformis. The most northern range of the 

 genus is at Senegal, West Africa, where, of five species, 

 two belong to distinct types, one, 0. acuminata, having a 

 representative on the coast of Sumatra in 0. subala, and 

 the other, 0. hiatula, a representative at Eeal Llejos, 

 Mexico, in 0. testacea. At Zanzibar on the opposite 

 shore of Africa is the characteristic 0. inftata ; and two 

 very peculiar species, 0. Indnsica and Ancillarioides, are 

 recorded from Kurrachee at the mouth of the Indus. 

 Three species from the coast of Brazil, 0. Brasiliensis, 

 patiila, and aquatilis, present forms which are quite pecu- 

 liar to that locality. Only two species, of very different 

 tyjiical character, arc recorded from the west coast of 

 South America, one of tolerable size and extremely vari- 

 able in colouring, 0. Periwiaua, the other of small dimen- 

 sion, 0. colmnellaris. Three species are described from 

 the Society and Feejee Islands, atid two from Australia. 

 The following may be noted as peculiar instances of 

 distribution. The only two species at present known 

 from the Eed Sea are identical with two inhabiting the 

 West Indies, 0. miitica and jaspidea. 0. reticularis, in- 

 habiting the Gidf of California, is found in a smaller state 

 in the West luilies. 0. Duclosi is found at the Philip- 

 pines in the Eastern Seas, and at the Society Islands in 

 the Pacific. 0. hdeontina inhabits the Gulf of California, 

 and also one of the Galapagos Islands. Lastly, we have a 

 species, O. crumda, from fom- different localities singularly 

 remote from each other, — the Philippine Islands, Zan- 

 zibar, Australia, and the Society Islands. 



Species 1. (I'ig. a, h, Mus. Steere.) 



Oliva anqulata. OVm. testa ovatd, venlricosd, crassis- 



siiud, ponderosd, supra medium angulato-tumidd, spird 



breviusculd, colmnelld valde callosd, planiplicatd, plicis 



fere obsoletis ; cinereo-albidd, oUvaceo et grlseo mar- 



November, IS 50. 



