EXOTIC CONCHOLOGY. 31 



PATULARIA ROTUNDATA. ROUND PATULARIA. 



Plate XXXVII. 



Testii ovnto-rotuiulata, infcquilatcrali, magnii, tumidu, transversim striatA, olivaceo-nigres- 

 cente ; linea cardinali hand rectii, : anticc rotuudatri ; postico latere longiore, 

 supenie subalato subtus subangulato, margine sinuoso : natibus prominulis, trans- 

 verse sulcatis : intus margaritacea. 



This species far infei'ior in elegance to the last, cannot even claim to he con- 

 sidered good looking, so somhre an appearance does the dark and unrelieved olive 

 of its epidermis give the shell. It is decidedly larger and coarser than Ovata and 

 far rounder, with the striae more apparent, the hinge margin curved and the um- 

 bones sulcated transversely. The sudden depression of the posterior slope raises an 

 angle running down from the bosses to the lowest extremity of the margin on that 

 side, which latter, after forming a slight beak, meets the hinge margin with much 

 sinuation. The slope is obliquely gi'ooved, the anterior end rounded, the valves 

 convex, and the inside pearly. Breadth four inches. Locality ? 



Family— AVICULIDiE. 



Animal attached, byssiferous : shells lamellar, internally perlaceous : the valves generally 



gaping. 

 Genus — Mutilus. Oblong, transverse, the bosses small, close to the anterior margin : 



both extremities rounded ; hinge margin straight, and generally forming an angle : 



valves not always gaping, teeth (except in Brachidontes) none. 

 Sub- Genus —M.ODio'Lii.. Umbones prominent, not terminal, hinge margin considerably 



angulated : the shell smooth and toothless : valves slightly gaping. 



MODIOLA ELONGATA. LENGTHENED MODIOLA. 



Plate VIII. 



Testii elongato-angusta, depresso-cylindracea laevigata ; spadicea ; margine superiore 

 recto, subalaeformi, depresso, inferiore vix arcuato : interiore facie margaritacea. 



This far from inelegant shell might possibly be confounded with the descriptions 

 of certain species by Lamarc, but careful comparison will prove its distinctness. Its 

 peculiar elongated appearance (fi'om which character it derives its name) gives it 

 the semblance of a winged Lithodomus, none however could fall into the error of 

 including it amongst them. The hinge margin is notable for its straightness, and 

 the almost entire freedom from arcuation of its lower margin, would of itself alone 

 separate it from most of the Modiolae. For the rest, the colour is chesnut, the inte- 

 rior nacre brilliant, the surface merely striated by the lines of growth, the shape 

 depressed-cylindraceous, transversely elongated, and all but winged. Three inches. 

 Locality ? 



