23 
Genus — MODIOLA, Lamarck^ 1799. 
(Prodrome — Mom. Soc. Hist. Nat. Paris, 1799, p. S7.) 
Modiola dunlopensis, SI ), noo . 
(PI. V, Pigs. 4 and 5 ; PI. VI, Pigs. 1 and 2 ; PI. VII, Pig. 1.) 
Sp. Char. — Shell transversely elongate, siib-solenoid, curved, moderately 
inflated, becoming gradually compressed towards the ])osterior. Cardinal 
margins gently arched ; ventral margins convex at the anterior ends and 
beloAV the umbones, then becoming concave or hollowed to the posterior ventral 
extremities, where they again swell out. Anterior ends small, gibbous, and 
the valves a 2 )parently gaping ; margins rounded. Posterior extremities 
compressed and expanded, the valves gaping ; margins rounded below, 
obliquely rounded above. Body of the shell more or less inflated, the greatest 
convexity at about half its length, the valves traversed by obtusely rounded 
arched carinae, gradually dying away towards the posterior ventral angles, 
but most prominent at the greatest convexities ; flanks below the carinae 
somewdiat hollowed out. Umbones sub-terminal, rather flattened. Sculptuer 
of close concentric laminae, parallel to the outlines of the ventral margins 
below the carinae, describing obtuse angles on passing over the latter, and 
then retiring above parallel to the oblique portions of the posterior margins. 
Ohs. — M. dunlopensis is a characteristic shell of both our Upper and 
Lower Cretaceous. Some years ago the late Mr. C. S. "Wilkinson sent to me 
(when in London) a Modiola from the Dunlop Holding Avell-boring that I then 
believed to be 31. flagelUfera, Porbes,^ from the Utatur Group of India 
It is, however, distinguished from Stoliezka’s flgures' of this shell by a 
less proportionate length, more arched cardinal margins, much more 
prominent and gibbous anterior ends, and is altogether a more robust and 
shorter form proportionately. Very similar features, omitting those of the 
anterior ends, distinguish our shell from 31. Bainii, Sharpe,^ of the South 
African Mesozoic rocks, in addition to the great prominence of the concentric 
laminations on crossing the carinm, Avhicb in this instance become riigte. 
Prom 3Iodiola plicata, Goldf.,‘‘ of the European Upper Jurassic, and 
its ally M. sowerhi/anus, D’Orb.,'’ of the Great Oolite, a higher degree of 
concavity of the ventral margins, more expanded i)Osterior ends, and a less 
' Wilkinson, Notes Geol. N. S. Wales (Dept. Mines, Sydney), 2nd Edit., 1887, p. 78. 
- Stoliezka, (Iret. Fauna S. India (Pal. liul.), 1S7I, 111, Pt.s. 5-8, p. 379, t. 24, f. 2. 
^ Trans. Geol. Soc., 1856, VII (2), Ft. 4, p. 193, t. 22, f. 2 and J 
‘ Petrefacta Germaniw, t. 1.30, f. 12« and \'2h. 
^ Mytilus, Morris and Lycett, Mon. Moll. Gt. Oolite, 1853, Pt. 2, p. 30, t. 4, f. 1. 
