48 CRETACEOUS PELECYPODA 



gaping posteriorly. The beaks are prominent and incurved towards the front. The 

 hinge of the left valve is composed of two teeth, the anterior of which is much 

 larger than the posterior, which very probably supported the cartilage (see. pi. xvi, 

 fig. 17*) ; the fulcra for the ligament are small. 



Locality. — In bluish calcareous sandstone at Garudamungalum and at Pondi- 

 cherry. 



i^orma^ioji.— Trichinopoly group, (? Valudayur group). 



3. PoROMYA SUPEEBA, StoUczM, PI. Ill, Figs. 2-4. 



P. testa ohlonga, crassa, tumida, postice hianti, valde incBquilaterali, antice 

 abrupte decUvi et siibrotundata, postice producta, suhtruncata ; umbonibus promi7ienti- 

 bus, latis, antice versus paulo incurvis ; superficie costidis ac striis incrementi con- 

 centricis, et nmllis lineis elevatis radiantibm spimilose tuberctdatis, sed in parte 

 postica sub-obsoletis ornata ; costidis concenti-icis ptrope unibones siiis precipue dis- 

 titictis, latis ac cequalibus. Cardo in idraque vatca dentibus duobiis instructus ; in 

 valva sinistra dens posticus, in dextra dens anticus, altera major. 



Height of the right valve : its length ... ... ... 0-69 



Thickness „ „ : v •■• ••• ••• 0-32 



This is a gigantic but typical species of Foromija, the shell is very globose, 

 inequilateral, the posterior side being much longer and subtruncate at the end ; the 

 anterior side is rather abruptly sloping and narrowly rounded. The surface is 

 covered with concentric lines and ribs, which are strongest and most prominent 

 near the umbones ; besides that there are numerous radiating lines provided with 

 small spiny tubercles, where they meet the former. When tlie spines are. broken off 

 small grooves appear in their place. This is exactly the structure of the shell of 

 the recent Foromijcc, and it is probable that the punctures which have been des- 

 cribed in the two previous species are only due to the removal of the spines. 



The hinge is composed of two teeth in each valve, and the fulcra are very 

 strong and prominent. In the left valve there is a rounded tooth in front, with a 

 f^roove on either side : in the anterior groove a small tooth of the right valve fits in ; 

 in the posterior lies the cartilage supported by a long, almost horizontal, tooth of the 

 opposite valve ; the posterior tooth in the left valve is represented by an oblique 

 rido-e, but distinct from the fulcrum. 



The largest specimen observed measures 130 m.m. in length and about 100 

 in height. 



Localitij. — In earthy and calcareous shelly sandstone near Garudamungalum, 

 and in a conglomerate near Koloture. 



Formation. — Trichinopoly group. 



• In fi". 9h on PI. II the hinge-teeth and cartilage process are not sufficiently clearly drawn. 



