THRACIA.— Plate III. 



Species 18. (Mus. Cuming.) 



Thracia oblonga. Thr. testa oblongd, subdepressd, la- 

 teribus rotundatis, postico parum angulato ,• sordidi 

 alba, granoso-scabrosd, concentrice rude striata. 

 The oblong Thracia. Shell oblong, rather depressed, 

 sides rounded, the posterior but little angled ; dead- 

 white, granosely scabrous, concentrically rudely stri- 

 ated. 

 Hub. Red Sea. 



Of simple form and character, but an interesting addi- 

 tion to the genus on account of its habitat. 



Species 19. (Mus. Cuming.) 



Thracia Novo-Zelandica. Thr. testa subtrigono-ovatd, 

 solidiusculd, pos/ice sub/ale angulatd, valvd sinistra 

 plana, concentrice rude plicato-striatd, pfeesertim ver- 

 sus umbones, umbonibus subacutis, subrosfratis ; albidd, 

 laevigata. 



The New Zealand Thracia. Shell somewhat trian- 

 gularly ovate, rather solid, posteriorly rather broadly 

 angled, left valve flat, concentrically rudely plicately 

 striated, especially towards the urnboes, umboes 

 rather sharp, a little beaked; whitish, smooth. 



Ilab. New Zealand. 



Of the same Myadora form as T. Australica, and pos- 

 sibly a variety of that species, but the specimens, so far as 

 they have been collected, appear however to be distin- 

 guished as in our figures. 



Species 20. (Mus. Cuming.) 



Thracia distorta. Thr. testa oblique subtrigono-ovatd, 

 cuneiformi, ijibbosd, rude plicato-striatd, latere postico 

 mul to longiore,jlexuoso, vie angulato, antico abbreviato, 

 rotundato, umbonibus subaiuplis, tumidis ; sordidi alba. 



The distorted Thracia. Shell obliquely somewhat 

 triangularly ovate, wedge-shaped, gibbous, rudely 

 plicately striated, posterior side much the longer, flexu- 

 ous, scarcely angled, anterior side shortly rounded, 

 umboes rather large, swollen ; dead-white. 



Mya distorta, Montagu, Test. Brit. p. 42. pi. 1. f. 1. 

 Anatiua distorta, Turtou. 

 Thracia distorta, Brown. 

 Anatiua rupicola, Lamarck. 

 An eadem var. ? Anatiua truncata, Turton. 

 Thracia truncata, Brown. 

 Thracia brevis, Deshayes. 

 Rnpicola distorta, De Bellevue. 

 Rupicola concentrica, De Bellevue. 



Bab. European seas, from Sweden to the Mediterranean, 



and from the Orkneys to the Channel Islands (in ten 

 to thirty fathoms water, on a stony bottom, and some- 

 times imbedded in limestone) ; Forbes and Hanley. 



Like most rock-inhabiting species, this is of very irre- 

 gular growth, and owing to its rude varieties and wide 

 geographical distribution, it has received several names. As 

 in T. cuneolus and in the following species from Malacca, 

 the posterior side is the longer, instead of being, as in all 

 other species of the genus, the shorter; and it cannot be 

 doubted that M. Fleurian de Bellevue's subdivision of the 

 group, as shown by our synonyms, is a very natural one. 



Species 21. (Mus. Cuming.) 



Thracia rddis. Thr. testa oblique ovatd, rude gibbosd, 

 irregulariter plicato-striatd, umbonibus amplis, tumi- 

 dis, latere postico graudiore, peranguste superficialiter 

 angulatd ; sordid!) alba. 



The rude Thracia. Shell obliquely ovate, rudely gib- 

 bous, irregularly plicately striated, umboes large, 

 swollen, posterior side the larger, very narrowly su- 

 perficially angled ; dead-white. 



Hub. Malacca. 



Obviously a rock-dwelling species belonging to subgenus 

 Rupicola, in which the posterior side of the shell is the 

 larger. 



Species 22. (Mus. ? ) 



Thracia granulosa. Thr. testa orato-oblongd, subee- 

 quilaferali, alba, undique minute granulatd, trans- 

 versim oblique plicata, plicis grandibus, undulatis, 

 ad latus posticum valva superioris obsoletis, latere 

 postico subtruncalo. 



The granuled Thracia. Shell ovately oblong, nearly 

 equilateral, white, everywhere minutely granulated, 

 transversely obliquely plicated, plaits large, waved, 

 on the posterior side of the upper valve obsolete, 

 posterior side subtruncated. 



Adams and Reeve, Moll. Voy. Samarang, p. 82. pi. 23. 

 f. 16. 



Hab. China Sea. 



This fine specie*, described about ten years ago in the 

 ' Zoology of the Voyage of the Samarang,' was dredged 

 in the China Sea by Captain Sir E. Belcher, and I am not 

 aware in what collection the specimen is deposited. It 

 belongs to the very characteristic wave-wrinkled type re- 

 presented in the West Indies, California, and Honduras 

 by T. plicata and magnifica, and would appear to be about 

 intermediate between ihem. It has the form of the variety 

 of T. plicata, Fig. 7 c, with the deeply sculptured folds of 

 T. maguijica. 



