Miscellanea. 199 
MonoGRaPH OF THE RECENT SPECIES OF TRIGONIA, INCLUDING THE 
DESCRIPTION OF A NEW SPECIES FROM THE COLLECTION oF H. 
Cuming, Esq. By Arruur Apams, R.N., F.L.S. ere. 
(Mollusca, Pl. ITT.) 
Triconia, Bruguiere. 
Testa equivalvis, inequilateralis, transversa, trigona, interdum sub- 
orbicularis ; dentes cardinales oblongi, lateraliter compressi, 
divaricati ; duo in valvd altera, utroque latere transversim sulcati ; 
quatuor in aliera, uno tantum latere sulcati ; ligamentum externum, 
crassum, marginale ; impressiones musculares due. 
Shell equivalve, mostly inequilateral, transverse, rather triangular, 
sometimes suborbicular; cardinal teeth oblong, laterally compressed, 
divaricated, two in one valve transversely grooved on both sides, four 
in the other grooved on one side only; ligament external, thick, 
rather short, marginal; muscular impressions, two, distinct, lateral ; 
palleal impression very nearly entire. 
Tricgonta Manrcaritacea, Lamarck. 7. testa suborbiculata, 
radiatim costata, intus margaritaced, costis elevatis, verrucosis, 
subasperis ; margine plicato. ' 
Shell rather compressed, with 20 or 23 rather narrow, nodulose, 
yadiating ribs; the hinder ribs very compressed, all excepting the 
front ribs wide apart. 
Hab. Van Diemen’s Land; Ronald Gunn, Esq. (Mus. Cum.) 
Trigonia margaritacea, Lamarck, Ann. du Mus, tom. iv. p. 355. 
pl. 67, fig. 2. 
T, pectinata, Lamk. 
Tricgonta Lamarcnu, Gray. T. testd subventricosd, solidd, costis 
20—26 angustatis planiusculis nodulosis radiantibus, costis gree 
postice confertis angustatis, costis omnibus confertis nodulosis. 
Hab. in Nova Hollandia. 
Shell rather ventricose, solid, with 20 to 26 narrow, flat-topped, 
nodulose radiating ribs; the ribs of the hinder slope narrow, rather 
crowded ; ribs convex, all close together and nodulose. 
Hab. New Holland, Port Jackson; Mr. Stutchbury. (Mus. Cum.) 
Varies, with the inside white, salmon-coloured, yellow, or purple 
bronze. 
Trigonia Lamarckii, Gray, Annals of Nat. Hist. 1838, p. 482. 
Triconia Juxest, A. Adams, n.sp. T. testa ovato-trigona, posticé 
truncata, margine sinuato, radiatim costatd, costis circa 20—24 
elevatis, tuberculato-nodosis, tuberculis rotundatis, obtusis, margine 
ventrali valdé pectinato. 
(Mollusca, Pl. III. figs. 4, 5, 6.) 
Shell ovately trigonal, posteriorly truncated, the margin sinuated, 
