40 TESTACEOUS MOLLUSCA. 
teeth two, oblong, compressed, short, and inserted ; ligament in- 
ternal, situated in a pit. 
E. Carpiores. Lam. 1.—Bl. t.73.f.7.—E. vol. 2. p. 117.— 
Del. t. 4. f. 7. Roundish, orbicular, small, decussated by trans- 
verse distant and longitudinal close set striee. ?.—Nem Holland. 
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 dividedin the middle ; ligament internal, inserted in a pit. 
U. Ostonea. Lam. 1.—Reeve. t. 46.—Bl. t. 73. f. 6. Con- 
vex, longer than broad, rounded when young, becoming elongated 

1 T 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. Georrroyi. Payr. Cat. t. 1. f. 3, 4, 5. Small, ovate- 
triangular, thin, flattish, snowy white, pellucid, shining, sub-equi- 
lateral, slightly striated transversely, adorned with small brown in- 
terrupted longitudinal lines, which seem to lie beneath the surface. 
2,— Mediterranean. 
If we may include the genus MONTACUTA of Turton in any of 
the Lamarckian genera, we must refer it to Erycma. 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. Ferruernosa.* Turt. B. p. 60.—Mya F. Mont. Sup. t. 
26. f. 2.—D. p. 46.—W. t. 2. f. 19. Oblong, slightly striated 
concentrically, white often covered with an ochraceous coat, very 
inequilateral, beaks obtuse : one of the teethin each valve erect, the 
other much bent inwards, and sloping downwards. +.—See too the 
M. Brpentrata. Turton.—(Mya. B. qe t. 26. f. 5.)—Also 
his M. Sussrriatra. Turt. B. t. 11. f. 9 § 10.—and his 
Ostonea. (Turt. B.t. 11. f. 11.2 Me 
See likewise the E. Fontenayi of Mittre in Revue Z. Cuv. 1814. 
