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A 



24 CRETACEOUS PELECYPODA 



III. MARTESIA, Leach, 1824, (see p. 20). 

 1. Mautesia ttjndenSjj Stoliczka, PL 11, Eigs. 5-6. 



Mart, testa cuneiformi, antice subinflata ac rotundata, postice attenuata et ad 

 terminationem svMruncata ; hiatu antico angusto ; superficie in area centrali subtile 

 striata, sulco mediano ab umbombus dectirrente divisa ; regione postica lateraliter 

 minute rugosa, area postica supra subcarinata ; impressione muscutari postica valde 

 elongata ; valr)ula accessa wnbonali parva, late ovata, antice emarginata ; marginibus 

 valvarum ante urnbones elevatis ac reflexis. 



The short, anteriorly inflated and globular form of this shell easily distinguishes 

 it from other known species. Young specimens (fig. 5) are more regularly club- 

 shaped, the attenuation of the valves from the front towards the posterior end being 

 more gradual than in old ones. The valves have a distinct, though very narrow 

 opening in front for the protrusion of the foot, the shelly covering being somewhat 

 prominent ; the surface of the central area is finely striated, and the strige pass over 

 the median groove almost continuously ; the posterior area is very slightly rugose. 

 The accessory valve covering the umbones is thin and anteriorly emarginated ; it is 

 rather broadly oval, but I have not been able to trace exactly its posterior margin. 



Locality .—M-OY^Yid^iooT ; boring in wood together with the next species. 



Formation. — Ootatoor group. 



IV. PAEAPIIOLAS, Conrad, 1848, (see p. 20). 

 1. Parapholas meesa, Stoliczka, PL II, Eig. 7- 



Paraph, testa elongata, cuneiformi, antice rotundata, subinflata, postice regula- 

 riter attenuata ; hiatu antico minimo ; superficie lateraliter minute striata, postice 

 supra lamellose rugosa; area centrali duobus sulcis approximatis ab umbonibus 

 ad peripheriam decurrentibus notata ; valvuUs accessis supra urnbones sitis inter se 

 contingentibus^ serriicircularibus ; valvida dorsali postumbonali stiliform/i, simplici ; 

 ventrali similariter constructa, sed longitudinaliter bipartita. 



This is a typical species of Parapliolas, having the umbonal accessory valve 

 divided longitudinally, but in every other respect the shell resembles a Martesia, 

 The two furrows running from the umbones towards the periphery are said to be 

 present in all known species of Parapholas ; there are, however, some species of 

 Martesia known {M, branchiata, Gld., and others) which also possess two umbonal 

 valves. On the other hand, there occurs a species in the Irawadi delta, described by 

 Mr. W. Blanford as Martesia fluminalis, (Journ. Asia! Soc, Bengal, vol. xxxvi 

 1867, p. 67, pL 3, figs. 1-3), which has a divided umbonal accessory valve, but only 

 one rib running from the umbones to the periphery, a second one being only internally 

 and not very distinctly marked ; it is almost parallel to the superior margins of the 

 valves. Still the species must be considered as a Parapholas and not as a Martesia 

 though I must again say that the distinction scarcely deserves to be reo^arded as 

 of generic value. 



