MTA. 207 



MUEICANTHIJS. Sw. A sub-genus of Murex, thus described : 

 " Yarices numerous, foliated ; spire sliort ; margin of the outer 

 lip with a prominent tooth near the base ; Eadix. Sw. Zool. 

 111. 2nd series, pi. 113, Melanomathus. En. Meth. 418. f. 2." 

 Sw. p. 296. The latter of the two species quoted, however, 

 does not agree with the description, having no prominent tooth 

 on the margin of the outer lip. 



MUEI GATED. (Muricatus.) Having sharp points or prickles. 



MUEICIDEA. Sw. A genus of " Muricin»," Sw. thus de- 

 scribed : " Spire more produced, as long oi* longer than the body 

 whorl ; varices numerous ; no internal channel at the top of the 

 aperture." Sw. p. 297, and consisting of the following incon- 

 gruous species, " Lamellosa. Chem. f. 1823, 4. Magellanica. En. 

 M. 419. f. 4. Peruviana. lb. f. 5. sentiCosa, lb. f. 3. scaber. En. 

 Meth. 419. f. 6. hexagona. lb, 418. f. 3. erinacea. Mart.f. 1026." 

 Sw. p.297. 



MUSCULAE IMPEESSIONS are the marks or areas formed 

 on the interior surface of shells by the muscular fibres .which 

 attach the animals to them. Lamarck has divided the Conchi- 

 fera into two kiads : 1st. Monomyaria, those which have but 

 one adductor muscle, and consequently have but one impression 

 in each valve, as the Common Oyster, fig. 180; 2nd. The 

 Dimyaria, those which have two, and consequently have two 

 impressions in each valve. There are other smaller impres- 

 sions in some shells besides the principal. The palleal impression 

 is a mark or scar passing near the margin of the sheU. See 

 Introduction. 



MTA. Auct. Fam: Myaria, Lam. Pyloridea, PL — Bescr. 

 Transverse, oval, thick, gaping at both extremities, rounded 

 anteriorly, acuminated posteriorly ; hinge with one large, dilate, 

 compressed tooth in one valve, and a suture in the other, con- 

 taining the cartilage ; muscular impressions two, distant, large, 

 irregular ; palleal impression with a large sinus. — Obs. Mya may 

 be known by the large, prominent, broad tooth in one valve. In 

 Anatina there is one in each valve, and, in Lyonsia, accessory 

 pieces. Lutraria has cardinal teeth and a ligamentary pit. Pew 



