MYOCHAMA. 67 
varices; spire prominent, acute; aperture oval, terminating in 
a posterior, partly closed canal; outer lip varicose; inner lip 
smooth, laminar; operculum horny, concentric, pointed. Obs. 
This genus contains some of the most exquisitely beautiful shells 
in existence, the richness of their colouring, the ramifications of 
the varices, would render most of the species, the finest possible 
subjects for the exercise of the painter’s art in still life. The 
most remarkable are the Rosebud Murex, with its pink-tipt 
fringes ; the Venus Comb, with its long rows of parallel spines ; 
the Ducal Murex, the Royal Murex, and many others which are 
much sought after by collectors. Murex may be distinguished 
from Triton by the continuity of the varices, which follow each 
other in a tortuous direction on the spire. The Ranelle have 
only two rows of varices, and have a posterior, as well as ante- 
rior canal; while Murices have three or more varices, and but 
one canal. Fig. 395 to 397. 
MUSCULR IMPRESSIONS. Are the marks or areas formed on 
the interior surface of shells, by the muscular fibres which at- 
tach the animals to them. Lamarck has divided his Conchifera 
into two kinds: Ist. 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 that have two, and consequently have two impressions 
in each valve. There are other smaller impressions in some 
shells, besides the principal. The Palleal impression isa line or 
scar passing near the margin of the shell. 
MY’A. (Mvoy, a muscle.) Fam. Myaria,Lam. Pyloridea, Bl. Descr. 
Transverse, oval, thick, gaping at both extremities, rounded an- 
teriorly, 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, broad, prominent tooth in one valve. In 
Anatina there is one in each valve, and also accessary pieces, Lu- 
traria has cardinal teeth and a ligamentary pit. Few species of 
Mya are known. They belong to the northern hemisphere. 
MYCETOPO'DA, or Mycetopus. D’Orb. Fam. Nayades, Lam. 
Descr. Shell elongated, soleniform, inequivalve, inequilateral, 
gaping anteriorly; with muscular impressions very complex. 
Fig. 151, M. solenoides. Obs. These shells are said to terebrate 
like Pholas. 
MYA’RIA. Lam. A family belonging to Lamarck’s order Con- 
chifera Dimyaria, containing the genera Mya and Anatina. To 
these may be added other genera enumerated in explanation of 
figures 69 to 76. 
MYOCHA’MA. Stutch. (Myaand Chama.) Fam. Myaria, Lam. 
Deser. Inequivalve, irregular, attached, sub-equilateral; attached 
