30 EXOTIC CONCHOLOGY. 



Were this species, but slightly more truncated anteriorly, found lying upon a 

 beach, and the closed valves not examined for their hinge, few would hesitate to term 

 it Mya Truncata so nearly does its outline (though rather too long horizontally) 

 resemble that shell. But to speak more technically. Its shape is oval, with the 

 anterior extremity of the upper margin deeply incurved and contracted, and the 

 hinge margin of course corresponding in its sinuosity. It is inequilateral, the pos- 

 terior end running almost parallel with the base or lower margin, which is incurved 

 beneath the hinge, whilst the anterior extremity which is far shorter, ends abruptly 

 and forms an obtuse angle. The umbones or bosses are smooth, eroded so as to 

 show the nacre and far from prominent. The interior is brilliant mother of pearl, 

 slightly tinged with pink, and the outer coating is uniform olive green. Length 

 three inches. Locality? 



Genus -PATULARIA. 



Shell nearly equilateral round or cordate ; no teeth. 



PATULARIA OVATA. TRAPEZIFORM PATULARIA. 



Plate XXXVI. 



Testa transversim ovata, fragili, tumida, pallide olivaceo-lutescente, posticfe subradiata : 

 Unea cardinali recta : pube elevata, compresso alata ; natibus prominulis laevigatis ; 

 facie interiore margaritacea, purpureo sub umbonibus picta. 



Anodonta Trapesialis, Lam. Anx. sans V. 6. p. 87. no. 11. Crouch's Lam. 9. fig. /. 

 Enc, Met. 205. fig. 1. a. b. Chem. 8. pi. 86. fig 762. 



This genus, the prototype of Anodoninaj in the circle of the Unionidse, is 

 characterised by the umbones being remarkably swollen or ventricose, and the shell 

 almost round. The present species however, does not participate in the latter cha- 

 racter so much as its congeners, its general shape being ovate, with the hinge 

 margin straight, somewhat ascending towards the posterior end, and forming obtuse 

 angles at both extremities, (which owing to the great convexity of the valves 

 are depressed) so as to give the fragile shell an almost winged appearance. The bosses 

 are very broad, smooth and prominent, and of a pale blue, whilst the rest of the 

 surface is covered by a light yellowish olive epidermis, semi-radiated towards the 

 posterior end by lines of a darker hue. The interior is pearly, with purple blotches 

 beneath the umbones. Size three inches and a quarter. Locality ? 



The specific name trapezialis given to it by Lamarc some time previously to 

 Mr. Swainson's appellation, must of course replace the latter. 



