MONOCEROS. 



Plate II. 



Species 5. (Miis. Cuming.) 



MoNOCEROs TUBERCULATUM. Mon. testd ovafd, bast nm- 

 bilicaid, spird brevi, plus minusve exsertd, anfractibus 

 mperne depressiusouUs, transversim pUcato-codatis, 

 codis angustis tubercidatis, tubercuUs compressls, supe- 

 rioribus valde promiuentioribus, costarum interstitili 

 sulcatis, aperturd oblongd, fauce lineatd ; lutescenfe- 

 albd, aperturd earned. 



The tuberculated Monoceros. Shell ovate, umbili- 

 cated at the base, spu'e short, more or less exserted, 

 whorls narrow, tuberculated, tubercles compressed, 

 upper ones verj' prominent, interstices between the 

 ribs grooved, aperture oblong, iuterior liueated ; 

 yellowish white, aperture flesh-tinted. 



Gray; Sowerby, Conch. Illus. Monoceros, fig. 9. 



Hah. St. Elena, West Columbia (in the crevices of rocks) ; 

 Cuming. 



Chiefly distinguished by the narrow compressed tubcr- 

 cled structm-e of the ribs. 



Species 6. (Mus. Cuming.) 



Monoceros grande. Mon. testd ovatd, crassd, spird 

 breviusculd, acuta, anfractibus superne concavis, trans- 

 versim costatis, costis graudibus peculiariter crebri- 

 squamatis, squamis utrinque depresso-fomicatis, sttbinde 

 latioribus, interstitiis pro/mide excavatis, liris minute 

 squamatis ornatis, aperturd ovatd, fauce lineatd, labro 

 laqueato, dente subelongato, compicuo ; purpureo-fuscd, 

 aperturd albd, columelld rvfo tinctd. 



The great Monoceros. Shell ovate, thick, spire rather 

 short, sharp, whorls concave round the upper part, 

 transversely ribbed, ribs large, peculiarly closely 

 scaled, scales depressly vaulted on either side, now 

 and then wider, interstices deeply excavated, orna- 

 mented with minutely scaled ridges ; aperture ovate, 

 interior lineated, lip fluted, tooth rather elongated, 

 conspicuous ; purple brown, apertm-e white, columella 

 tinged with red. 



Gray, Zool. Beechey's Voyage, p. 124. 

 Purpura (rrayi, Kiener. 



Hah. James Island, GaUapagos, (in the clefts of rocks at 

 low water) ; Cuming. 



M. Kiener appears to be unacquainted with the beauty 

 and grandeur of this magnificent species, having questioned 

 the propriety of Mi-. Gray's generic arrangement of it 

 merely from the circumstance of liis having no other than 

 a young specimen, in which the tooth was scarcely deve- 

 loped. 



Species 7. (Mus. Cuming.) 



Monoceros muricatum. Mon. testd ovatd, spird pecu- 

 liariter depreaso-truncatd, anfractibus superne planatis, 

 iransversim costatis, costis, quarum superioribus valde 

 majorihus, tuberculatis et creberrinie squamatis, cos- 

 tarum interstitiis sulcatis et squamatis ; columelld pla- 

 niusculd; aperturd semi-ovatd, fauce lineatd; carneo- 

 fuscd, colmneUd labroque rufescentibus. 



The prickly Monoceros. Shell ovate, spire peculiarly 

 depressly truncated, whorls flattened round the upper 

 part, transversely ribbed, ribs, the upper of which are 

 much the largest, tuberculated and closely scaled, 

 interstices between the ribs grooved and scaled ; colu- 

 mella rather flattened ; aperture semi-ovate, interior 

 lineated ; fleshy brown, lip and columella reddish. 

 Purpura muricata, Broderip, Pro. Zool. Soc, 1833, 



p. 12.5. 

 Purpura truncata, Duclos, Magazin de Zool., 1833, 

 pi. 22. f 2. 



Hab. St. Elena, West Columbia (in the cre\'ices of rocks) ; 

 Cuming. 



The M. muricatum is chiefly distinguished from the 

 M. tuberculatum by its more depressed form, and by the 

 peculiarly broad squamate structure of the ribs ; there is a 

 close aflinity between them, but the series of each species 

 in various stages of growth, in Mr. Cuming's collection, 

 sufficiently demonstrate the dyference in their specific 

 character. M. Duclos' figure, like M. Kiener's of the 

 preceding species, is evidently drawn from an immature 

 toothless specimen. 



September, 1846. 



