Hiatella. MOLLUSCA. SOLENID.E. 461 



Tellina depressa, Penn. Brit. Zool. iv. 87- t. xlvii. f. 27 — T. variabilis, 



Don. Brit. Shells, t. xli. f. 2 S. vesp. Mont. Test. Brit. 54 — Psani- 



mobia vespertina, Turt. Biv. Brit. 92. t. vi. f. 10 — Southern coasts of 

 England and Zetland. 



Length an inch and a half, breadth 3 inches ; opaque ; cuticle dark-brown, 

 with purplish longitudinal rays ; striae on the retral extremity coarse ; a slight 

 oblique fold from the beaks to the hinder extremity ; one of the teeth in one 

 valve thin, laminar, and oblique. 



572. S. deflorata. — Valves convex, obsoletely truncated re- 



trally, with numerous waved longitudinal striae, crossed by the 



layers of growth. 



Venus den. Linn. Syst. i. 1133. Perm. Brit. Zool. iv. 96. t. lvii. f. 54. 

 Mont. Test. Brit. 123. t. iii. f. 4.— Psammobia defl. Turt. Biv. Brit. 93. 



South coast of England, rare. 



Length an inch, breadth an inch and three quarters ; purplish ; from the fold 

 to the margin behind the cartilage, the longitudinal striae are large and rough ; 

 two teeth in each valve, one of them small. 



EXTINCT SPECIES. 



1. S. Hollowayisii Depressed, transversely elongate, ovate, and striated ; 



posterior side gradually expanded ; anterior side very small — Sower. Min. 

 Conch, t. clix. — London Clay. 



2. S. undulata. — Three times as wide as long, transversely undulated ; con- 

 vex ; anteriorly rounded, posteriorly subtruncate, gaping a little ; beaks pro- 

 minent Sower. Min. Conch, t. Dxlviii. f. 1, 2. — Inferior Oolite. 



3. S. gibbosa Three times as wide as long, gibbose, smooth ; sides rather 



acuminated, a little gaping — Sower. Min. Conch, t. Dxlviii — Carboniferous 

 Limestone, Queen's County, Ireland. 



Gen. CXXXVII. HIATELLA— Transversely oblong ; dor- 

 sal and ventral margins nearly parallel; hinge with the 

 teeth obscure, or with one tooth in one valve received into 

 a cavity in the other. 



573. H. rugosa. — Rounded anteally, subtruncated retrally, 

 itl 

 gin. 



with a slight constriction towards the middle of the ventral mar- 



Pholas noster, List. An. Ang. 172. t. iv. f. 21 — Mytilus rugosus, Linn. 

 Syst. i. 115G. Mull. Prod. 249. Zool. Dan. t. lxxxvii. f. 1, 2.— Mya 

 byssifera, Fab. Green. 408.— Mytilus rugosus, Penn. Brit. Zool. iv. 



110. t. lxiii. f. 72. Mont. Test. Brit. 164 Saxicava rugosa and S. Pho- 



ladis, Turt. Biv. Brit. 20. t. ii. f. 10 — In cavities of limestone and the 

 roots of fuci. 



Length half an inch, breadth an inch and a half; white, with a greyish 

 wrinkled cuticle; irregularly sulcated concentrically; the ridges most conspi- 

 cuous on the angle from the beaks to the retral extremity ; the animal em- 

 ploys a byssus, when not lodged in the cavity of a stone. 



" 574. H. arctica. — Shell with two diverging spinous ridges 

 from the hinge to the retral extremity- 



