67 
striatissima, incrementi sulcis profundioribus, irregularibus, in- 
terrupta, intus extusque candidissima, nitente, utroque latere 
equaliter declivi, antice obtusa, postice acuminata, obtuse an- 
gulata, umbonibus minimis, acutis, oppositis; lunula areaque 
levigatis ; cardine crasso, lato, fossula mediana, dente cardi- 
nali angusta, obliqua, dentibus lateralibus validis, equalibus ; 
sinu pallit brevi, lato, obtuso, obliquo. 
Hab. Australia, Swan River. Coll. Cuming. 
23. Macrra CARINULATA, Desh. WM. testa trigono-transversa, 
tumida, cordiformi, equilaterali, sub epidermide squalide fus- 
cescente alba, obsolete irregulariter striata, equaliter superne 
declivi et convexiuscula; latere antico obtusiusculo, postico 
attenuato, angulo paulo prominente, obtuso distincto ; lunula 
indistincta areaque levigatis; umbonibus angulatis, prominenti- 
bus, acutis, obliquis, valde distantibus ; cardine solidiusculo, fos- 
sula trigona, obliqua, profunda ; dentibus lateralibus solidius- 
culis, simplicibus, elongatis, subequalibus ; sinu pallii angusto, 
profundo, oblique ascendente. 
Hab. ? Coll. Cuming. 
24. Mactra aneusta, Desh. WM. testa ovato-transversa, an- 
gusta, subtrigona, subequilaterali, compressa, alba, tenui, fra- 
gili, transversim argute et regulariter striata; latere antico 
paulo breviore, obtuso, superne concaviusculo, latere postico 
superne declivi, attenuato; area angusta, elongata, planulata, 
liris duabus parum divergentibus circumscripta ; umbonibus 
minimis, parum obliquis, regulariter undato-plicatis ; lunula 
minima, lanceolata; cardine in medio lato, fossula lata, 
trigona, explanata; dentibus lateralibus brevibus, inequali- 
bus, postico breviore; sinu pallit oblongo, horizontali, apice 
obtuso. 
Hab. Panama. Coll. Cuming. 
25. Macrra spitineata, C. B. Adams, MSS. WM. testa ovato- 
transversa, angusta, depressa, inequilaterali, translucida, alba, 
sub epidermide pallide flavicante, tenuissime striata in latere pos- 
tico fuscescente, latere antico declivi, obtusiusculo, attenuato, 
postico declivi, latiore, oblique truncato, in truncatura hiante, 
lineis binis, obliquis, albis, divergentibus distincto ; area an- 
gusta, plana; lunula indistincta ; umbonibus minimis, vie pro- 
minentibus, oppositis; cardine lato, fossula magna, lata, basi 
prominente, dentibus lateralibus brevibus, subequalibus ; sinu 
pallii magna, lato, profundo, semi-elliptico. 
Hab. Jamaica. 
26. Macrra suuuata, Desh. WM. testa ovato-subrotundata, in- 
fata, inequilaterali, tenuissima, fragili, membranacea, sub epi- 
dermide pallide flavescente albo-hyalina, antice oblique gibbosa, 
postice attenuata, late truncata, hiante, latere antico paulo 
longiore, late rotundato, transversim satis regulariter plicata et 
