300 Zoological Society. 



Genus Triomphalia*. 



Char. Gen. — Molluscum acephalum terebrans. Testa bivalvis, setate 

 juniore hians, aetate matura clausa. Valvse insequales ; utraque an- 

 tice lamina testacea inflata ad marginem ventralem affixa, interne 

 cardine unidentato, sine processu subcardinali. Valva dextra postice 

 alteram longitudine superans. Valva sinistra alteram involvens, ad 

 dorsum nucleo quasi-umbonali incipiens. 



The shells of this genus, wheii mature, have the ventral hiatus closed 

 by an expanded test fixed to the edge of each valve ; that of the left 

 valve commences at the back, in a nucleus resembling an extra umbo, 

 and in front overwrapping that of the other. The right valve, on 

 the other hand, materially exceeds in length, at the posterior extre- 

 mity, the other valve, which terminates very abruptly. The hinge is 

 without sub-umbonal processes, but has an obtuse tooth on the hinge 

 in each valve. 



The name is taken from the nucleus of the covering-test in the 

 right valve, which forms, as it were, a third umbo. The typical spe- 

 cies is the Pholas globosa of Quoy. 



Triomphalia GLOBOSA. (Pholas globosa, Quoy.) Tr. testa sub- 

 ovali, jiostice subattemiatd, antice ylohosd ; valvis transversa 

 dimidiatis, parte posticd concentrice lyratd ; in medio costd im- 

 hricatd unicd, parte anticd lyratd, radiatim costis acute imbri- 

 catis ornatd : valvd dextrd productd sublinguiformi, dentibus 

 aciitis recvi'vis serratd : nucleo lamince terminalis valves sinistrcB 

 trianfjulari, striatd, subcomplanatd. 



Found in soft stone, at half-tide. Island of Leyte ; Cuming. 



Triomphalia pulcherrima. Tr. testd subovali ventricosd, 



antice globosa, corrugatd, antice subattenuatd ; valvis transverse 



dimidiatis, parte posticd costis distantibus concentrice lyratd, 



parte anticd lineis lyratd, margine dentibus acutis crispatis 



serratd : nucleo lamince terminalis valvce sinistrce svbtriangulari, 



rotundo, lineis elevatis lyrato. 



This species is much larger than Tr. globosa, the ventral covering 



much more rough and inflated, the concentric ribs on the posterior 



part of the valves more strongly defined, and not crossed by the oblique 



row of raised points which is seen in the former species. 



Found in soft stone at low water at West Colombia ; Cuming. 



Triomphalia Cumingii. Tr. testd rotundd, crassd ; valvis 

 postice canali divisis, concentrice lineis elevatis lyratis, antice 

 costis minutis serratis radiatis ; parte posticd concentrice lami- 

 natd ; valvd dextrd postice in lingulam triangularem margine 

 triplicatam productd ; valvd sinistrd postice brevissinid margine 

 termin a li circu lari . 

 This shell would be completely spherical but for the linguiform ex- 

 tension of the right valve. The left valve terminates in a circular mar- 

 gin, where the rounded part of the right valve meets it. 



* Tpeis, tres \ oncpaXos, umbo. 



