124 
impression, and the hinge, prove it to be different from each of those 
species. 
11. Cycnina sPLENDIDA, Rémer. C. testa subquadrato-orbicu- 
lari, lentiformi, viz altiore quam longa, tumida, subinequilaterali ; 
concentrice grosse lirata, liris in parte inferiore remotis, rotun- 
datis, in medio subregularibus, extremitates versus irregulariter 
confluentibus, bifurcatisque, postice tumidioribus, liris ad umbonum 
regionem sensim densioribus, denique tenuissimis ; interstitiis 
transversim striatis ; nitida, pallide crocea, marginibus albidis ; 
umbonibus tumidis, valde prominulis, incurvis, fere contiguis, in = 
longitudinis collocatis ; margine ventrali medio dependente, sub- 
rotundato, tum in utroque latere oblique et subrecte adscendente ; 
margine dorsali regulariter curvato, postice valde prosiliente et in 
utraque extremitate cum margine ventrali angulum vix distinctum, 
rotundatum formante ; lunula areaque nullis, ligamento occulto, 
longe conspicuo ; pagina interna luteo-alba, ad marginem pallidis- 
sime albido-c@rulescente ; sinu palliari magno, late triangulari, 
valde sursum directo, in apice. rotundatim biangulato, lineis sub- 
rectis incluso ; lamina cardinali lata, planissima, dentibus in valva 
sinistra fere equaliter configuratis, tertio in valva dextra 
crassissimo, subprofunde bisulcato ; margine interiore subdense 
denticulato. 
Long. 46, alt. 48, crass. 27°5 mill. : 
Hab. Japan. 
The characters of this pretty shell bear a strong resemblance to 
those of C. flavida of Deshayes, and it was after much hesitation that 
I decided to separate it as species. I find it differing, in its more 
quadrangular outline, in its more oblique shape, the umbones being a 
little nearer to the anterior extremity, in the absence of the longitu- 
dinal lines, which are present at the hinder part of C. flavida, in the 
broader sinus of the pallial impression which is biangulated at the 
apex, and in the character of the hinge, viz. the teeth in the left 
valve being all of similar strength, and the third tooth in the right 
valve very much elevated, produced, and deeply divided. 
12. Cyctrna BomBycrINaA, Romer. C. testa fere exacte orbiculari, 
solidiuscula, antice rotundatim productiuscula, lentiformi, modice 
tumida, subequilaterali ; concentrice dense lirata, liris rotundatis, 
ad apices tenuissimis, basin versus sensim vit crassioribus, medio 
regularibus, ad extremitatem posticam rudibus, irregulariter con- 
fluentibus , lineis longitudinalibus impressis, cerulescentibus, per 
liras concentricas interruptis, medio exilissimis, densissimis, ad 
latera, precipue postice, remoticribus, expressioribus ornata ; 
colore e zonis pallide cerulescentibus et flavicantibus mizto, super- 
ficie serico simili nitente ; umbonibus acutiusculis, subrecte elevatis, 
incurvatis, contiguisque, vix medianis ; lunula areaque nullis ; 
ligamento immerso, conspicuo ; pagina interna albida, medio fla- 
vicante, supra pallide cerulea, ad marginem ianthina ; sinu palliari 
mediocri, sublate aperto, in apice anguste rotundato, lineis inclu- 
