4 23 
distantes, laterales; impressio muscularis pallit sinu brevi lato; 
ligamentum tenue externum. 
Shell inequivalve, adhering ; the attached valve with two unequal 
diverging marginal teeth, separated at the umbo by a triangular pit 
in which one end of a testaceous appendage is inserted and connected 
by a horny cartilage ; the free valve with two unequal, small, diverging 
teeth, close under the umbo, in which is inserted the other end of 
the testaceous appendage ; the umbo of the free valve is curved in- 
wards, that of the fixed valve outwards; muscular impressions two, 
nearly orbicular, distant, lateral ; palleal impression with a short broad 
sinus. 
MyocHaMA ANoMioIDES, Stutchbury. M. testa rosed, tenut, 
fragili, costis prominentibus radiantibus dichotomis ; valvd li- 
herd valde convexd ; umbone extra apicem valve alterius pro- 
ducto; epidermide tenui pellucidd. 
Long. 12; lat. 35 alt. 34. 
Hab. 
Shell rose-coloured, thin, fragile, ornamented by prominent radia- 
ting dichotomous ribs; free valve extremely convex, the umbo pro- 
jecting beyond the apex of the other ; epidermis thin and transparent. 
Hab. 
This species is always regularly radiately ribbed, but when found 
attached to smooth shells the ribs are smooth, but if fixed to Trigo- 
nia pectinata they are crossed by tubercles. 
Myocuama TRaNsversA, A. Adams. M. testd inequilaterali 
transversd fused, subquadratd, anticé longiore posticé breviore 
subtruncatd, radiatim costatd, costis subnodosis interdum di- 
chotomis, concentrice minutissimé striatd, valvd liberd subcon- 
verd, umbone extra apicem valve alterius producto. 
(Mollusca, Pl. VIII. fig. 1.) 
Shell inequivalve, transverse, light brown, subquadrate, anteriorly 
longer, posteriorly shorter and rather truncated, radiately ribbed, ribs 
rather nodulous, sometimes divided in two, very minutely concentric- 
ally striated, the free valve rather convex, with the umbo produced 
beyond the apex of the other valve. 
‘Hab. Cape Upstart, 8 fathoms; Mr. Jukes. (Mus. Cuming.) 
Myocnama Strancer, A. Adams. M. testd luted, tenui, fragilt, 
corrugatd, costis nodosis, non distinctis, concentrice striatd, 
lineis radiantibus asperis ad marginem ventralem distinctiori- 
bus; valvd liberd depressd umbone plano cinerascente non extra 
apicem valve alterius producto. 
Hab. in Australasia. (Mollusca, Pl. VIII. fig. 2.) 
Shell yellow, thin, fragile, corrugated, ribs nodulous, not distinct, 
concentrically striated, with rough radiating lines more distinct to- 
wards the ventral margin; the free valve depressed, ash-coloured, 
flattened, not projecting beyond the apex of the other valve. 
Hab. Port Jackson; Mr. Strange. (Mus. Cuming.) 
