107 



narrower, with more numerous whorls. No details of ornament 

 accompany the diagnosis. T. austrina, Watson, from Kerguelen, 

 is somewhat broader, the whorls more numerous, not so quad- 

 rate, and the two carinating lirse not equally disposed. 



Chione permagna, spec. nov. Pi. ii., fig. l. 



Shell triangularly oval, very thick, somewhat heart-shaped,, 

 very inequilateral, depressedly convex. Umbones large, de- 

 pressed, situated in about the anterior one-fourth. 



Post-dorsal margin arched, gradually merging into the 

 obliquely subtruncated posterior margin ; post-ventral margin 

 nearly straight, rapidly incurving to the rounded anterior margin ; 

 antero-dorsal margin cordately curved ; inner margin of valve 

 quite entire. Lunule broadly elliptic, shallow, its margins 

 angulated. 



Ornamentation of crowded . depressed growth-ridges and lines, 

 not raised into lamellae ; and on the dorsal-half by rounded 

 radial threads with equidistant interstitial furrows, about thirty 

 in a width of ten millimetres. 



Antero-posterior diameter, 86 ; umbo-ventral diam., 79 ; 

 sectional diam., 40. A larger and more orbicular example has 

 ant. -post, diam., 95 ; umbo-ventral diam., 88. 



This large ponderous shell is probably the largest in the genus, 

 hence its specific name ; it is distinguishable by its obliquely 

 orbicular outline. 



Chione Hallii, spec. nov. Plate ii. , fig. 5. 



Shell oblong-oval, moderately convex, somewhat thick,, 

 inequilateral ; concentrically grooved, the depressed rounded 

 intervening folds about two times as wide as the grooves, which 

 are somewhat variable in width, from 16 to 20 in a width of 

 ten millimetres near the ventral margin. Internal margin oi 

 valves quite entire. 



Antero-posterior diameter, 47 ; umbo-ventral diam., 38 ; sec- 

 tional diam., 21 mm. 



Most like C. tristis, Lamk., but the anterior side is more 

 developed, more cordate, the post-dorsal margin more arched, and 

 the concentric folds narrower and more numerous. 



Chione Kergueleni, spec. nov. PL ii. , fis;. 2. 



Oval-cordate, subventricose. Post-dorsal margin regularly 

 convex ; ventral margin slightly curved, rising rapidly to the 

 anterior margin ; interior margin quite entire. 



Ornamented with depressed concentric ridges, separated by 

 narrow deep sulci ; about eight ridges in a width of ten milli- 

 metres at the front (but the various examples show considerable 

 variation in the number of the growth-ridges) ; faintly radiately 

 and densely striated at least on the sub-surface shell-layer. 



