MITBA. 20J 



graph contains three species. Hx. M. brevialia. PI. xx^dii.. fig. 

 591. 



MESODESMA. Desh. Ektcina, Lam. according to Gr. B. 

 Sowerby. 



MESOMPHTX. Eafinesque. A genus proposed to be separated 

 from Helix, Auct. 



MICEOTOMA. Sw. A genua of « Purpurinje," Sw. thus 

 described, " Pillar very broad and curving inwards ; aperture 

 effuse ; the notch at the base small and nearly obsolete ; spire 

 very short, patula. Mart. 69. f. 758, 759. Persica. En. Meth. 

 897. f. 1. unicolor. Sw. Chem. f. 1449. Sw.p. 301." Purpura 

 Persica. Pig. 414. 



MILIOLA. Lam. A genus of microscopic Poraminifera. 



MISILUS. Montf. A genus of microscopic Poraminifera. 



MITEA. Lam. {Mitre.) Fam. Columellaria, Lam. Angyosto- 

 mata; Bl — Descr. Oblong, thick, covered with a light brown 

 epidermis ; spire long, turrited, acute ; aperture emarginated 

 anteriorly ; outer Kp thickened ; columella with several obHque, 

 thick plaits. — Obs. The pretty shells composing this genus differ 

 from Marginella, not only in general form^ but in the outer Hp 

 not being reflected. Some species of Yoluta, of a more elongated 

 shape than the rest, present a near approach to the most ven- 

 tricose of the Mitrae. The apex of Mitra, however, is always 

 acute, while that of Voluta is generally papillary. The aperture 

 of the former is narrow and the inner lip thickened, the contrary 

 being the case with the latter. The shells of this genus are 

 varied in coloxm^ng, which is generally rich ; and also in form, 

 some being angulated, some plicated, some coronated and 

 others smooth. The species are mostly tropical ; very few occur 

 so far north as the Mediterranean. Possil species are nume- 

 rous in the Eocene beds. Pig. 431. M. Plicaria. Pig. 432. 

 Conohelix marmorata, Sw. PI. xx. — The Mitrae are thus divided 

 in Gray's British Museum arrangement : Mitra, typified by 

 the common M. episcopahs ; Zierliana, Gray, certaia short, 

 thick-lipped strombiform species, M. Ziervoglii ; Turris, Montf. 

 of which our figure is an example ; Cylindra, like Conohelix, but 



