BIYALVIA. 05 



This species much resembles M. Bernayi, Desh. (An. saus Vert, du Bassin de Paris, 

 I. LI, p. 13, PI. 74, figs. 13 — 10), particularly in the outline, but it differs in having a 

 smaller pedal region. Our shell is ornamented between the rays on the siphonal region 

 with elevated ridges or regular lines of growth, decussating, as it were, the interspaces. 



Fig. 15 is the cast of a shell in the late Mr. Dixon's collection of Eocene fossils in the 

 British Museum; unfortunately it is without a locality. It resembles in outline the above 

 species. 



4. Modiola DOltSATA, Morris. Tab. XIII, fig. "2. 



Modiola doksata. Morris. Geol. Joimi., vol. x, pt. i, p. 158, pi. 11, fig. 1 !, 1854. 



" A rare species. The specimen is hardly sufficiently perfect for an exact determination 

 of its characters. It differs from the preceding species (M. Mitchelli) in the umbo not 

 being so terminal, and the form being less spathulate and more compressed." {Morris.) 



Locality. Sundridge (Prestioich). 



The only specimen that I have seen is the one figured, and I am unable to add to the 

 description given by the proposer of the species. The prominent diagonal ridge is pro- 

 bably accidental, but the pedal side is considerably extended, if it be natural and not 

 forced out by pressure. 



5. Modiola elegans, ./. Sowerbg. Tab. XII, fig. 5, a — c. 



Modiola elegans. J. Sow. Min. Conch., t. ix, left-hand figures. 



— — J. Morris. Catal. Brit. Foss., p. 211, 1854. 



Mytilus elegans. lyOrhigny. Prod, de Pal^ont., p. 391, 1850. 



Spec. ('liar. Testa lenui, ovnto-elongatd vet subtrapezoidali, tumictd, subcarinatd; 

 pedi-regione brevi, siphoni-regione rotunda; man/hie dorsali pauto angulafo ; striis 

 uiroque divaricatis, spafio mediano lavigato ; margine ventrali subrecto. 



Shell thin, elongately ovate or subtrapezoidal, tumid, and obtusely keeled ; pedal region 

 short and rounded ; dorsal margin obtusely angulatcd or curved ; striae on both sides 

 divergent, middle plain ; ventral margin slightly contracted; shell nacreous. 



Length, \\ inch. 



Localities, a, Highgate {Wetherett), Bognor, Richmond Park (J. Sowerbg), Clewer 

 (irecn ? (Prestwic/i) ; e, Bracklesham, Barton (Fd/cards) ; b, Hordwell (Bdtvards). 



This appears to have extended from the lowest to the uppermost of the Eocene 

 deposits; it is not rare, and is subject to considerable variation. It is less pointed on the 

 pedal side than M. hastata. Our shell is thin, and some specimens are so irregularly 

 tumid as to form an obtuse keel or ridge from the umbo to the edge of the ventral margin 

 of the siphonal region, but in others this is by no means prominent, as if this keel were 



9 



