190 MONILEA. 



MITRELLA. Sw. A genus consisting ofMiTRA Fissurella, casta, 

 Olivseformis, and similar species, described as " Rather small ; 

 olive-shaped; unequally fusiform; always smooth and polished, 

 and sometimes covered with an epidermis; base obtuse and effuse; 

 spire nearly or quite equal to the aperture; plaits of the pillar 

 few, oblique, and extending beyond the aperture, which is 

 smooth internally." Sw. p. 321. M. Fissurata, E. M. 371. 

 f. 1. Olivarii, f. 2. Dactylus. 372. f. 5. Ex. Mitra bicolor. 



MITREOLA. Sw. A genus of "Mitranse," Sw. thus described : 

 " Small ; unequally fusiform; the base obtuse; inner lip, typically 

 thickened, inflected, and either toothed or tuberculated ; plaits 

 on the pillar distinct, the inferior largest ; tip of the spire 

 sometimes papillary; aperture without either strise or groove." 

 Sw. p. 320, M. Monodonta, M. Terebellum. Zool. Illustr. II. 

 128. f. 1. f.2. 



MODIOLA. Lam. (Modiola, a little measure.) Fam. Mytilacea, 

 Lam. — Descr. Equivalve oblique, cuneiform, inequilateral, thin, 

 with the anterior side short and narrow, slightly gaping to admit 

 the passage of a byssus, and the posterior side elongated, broad, 

 sub quadrate; hinge thin, toothless, rectilinear, with a long, 

 partly external ligament ; muscular impressions two in each 

 valve; palleal impression irregular, not sinuated. — Obs. This 

 genus differs from Mytilus, to which the common muscle belongs, 

 in the anterior margin being rounded out beyond the umbo, 

 which in Mytilus is terminal. The Lithodomi may be known 

 from this genus by their cylindrical form. Fig. 160, M. Tulipa. 



MOLLUSCA. (From Mollis, soft.) The twelfth class of inverte- 

 brated animals with univalve shells or none ; divided into the 

 following orders: Pteropoda, Gasteropoda, Trachelipoda, Cepha- 

 lopoda, Heteropoda, fig. 220 to 488. The term mollusca is 

 also used in a general sense to include the classes Conchifera 

 and Mollusca of Lamarck, corresponding with the type Malacozoa 

 of De Blainville. 



MONEY COWRY. Cypraea Moneta, which passes current in some 

 parts of Africa and the East Indies. 



MONILEA. Sw. A sub-genus of Monodonta. Sw. p. 352. 



