40 TESTACEOUS MOLLUSCA. 



teeth two, oblong, compressed, short, and inserted ; ligament in- 

 ternal, situated in a pit. 



E. Cardioides. Lam. l.—Bl. U73./.7 .—E.vol.2.p. 117.— 

 Del. t. 4. f. 7. Roundish, orbicular, small, decussated by trans- 

 verse distant and longitudinal close set striae, f . — New Holland. 1 



UNGULINA. 



Longitudinal, sub-transverse, rounded at the ventral margin, sub- 

 equilateral, with the valves closed ; beaks decorticated ; one short 

 primary cleft tooth in each valve, with an oblong marginal 

 groove divided in the middle ; ligament internal, inserted in a pit. 



U. Oblonga. Lam. 1. — Reeve, t. 46. — Bl. t. 73./. 6. Con- 

 vex, longer than broad, rounded when young, becoming elongated 



1 I have seen Lamarck's own specimen of this (the only recent 

 species mentioned by him) and can aver with certainty, that it does 

 not belong to this genus, as the ligament is clearly external. It 

 appears much more like an aberrant Venus. M. Deshayes dwells 

 much on the error (as he considers it), of Mr. Sowerby's uniting 

 Mesodesma with this genus. I hardly know any one, who, on 

 reading carefully Lamarck's characters, would not have come to the 

 same conclusion, although assuredly few if any of the fossil species 

 could be classed with the latter genus, the majority of them as well 

 as the recent E. GeofFroyi of Payraydeau, approximating much more 

 closely to the genus Kellia of Turton. 



E. Geoffroyi. Payr. Cat. t. 1. f. 3, 4, 5. Small, ovate- 

 triangular, thin, flattish, snowy white, pellucid, shining, sub-aequi- 

 lateral, slightly striated transversely, adorned with small brown in- 

 terrupted longitudinal lines, which seem to lie beneath the surface. 

 |^. — Mediterranean. 



If we may include the genus MONTACUTA of Turton in any of 

 the Lamarckian genera, we must refer it to Erycina. I extract its 

 characters from Turton's British Bivalves, p, 59. " Oval or oblong, 

 equivalve, inequilateral, mostly closed ; hinge with two teeth in 

 each valve and a cavity between them, lateral teeth none ; ligament 

 internal." 



M. Ferruginosa.* Turt. B. p. 60.— Mya F. Mont. Sup. t. 

 26./. 2.—D.p.46.—W. t. 2./. 19. Oblong, slightly striated 

 concentrically, white often covered with an ochraceous coat, very 

 inequilateral, beaks obtuse : one of the teeth in each valve erect, the 

 other much bent inwards, and sloping downwards. ^. — See too the 

 M. Bidentata. Turton.— (My a. B. Mont. t. 26. /. 5.)— Also 

 his M. Substriata. Turt. B. t. 11./. 9 $• 10.— and his 

 Oblonga. {Turt. B. t. 11./. 11. 2.) 



See likewise the E. Fontenayi of Mittre in Revue Z. Cuv. 1814. 



