PECTUNCULUS.— Plate I. 



shining chestnut colour, crenated ; epidermis thick 

 and hairy. 

 Hab. Guaymas, Gulf of California. (Found in sandy 

 mud at seven fathoms depth.) 



This magnificent shell, which was brought from the 

 above port by Mr. Babb, R.N., accords in some measure 

 with Lamarck's description of his Pectunculus undulatus. 

 The figure in Delessert's ' Recueil de Coquilles,' how- 

 ever, of that shell, fully exhibits its specific difference. 



Species 4. (Mus. Cuming.) 



Pectunculus maculatus. Pect. iestd orbiculari, sub- 

 auritd, submquilaterali, convexd; albente, castaneo- 

 maculosd, striis radiantibus subdecussatis, creberri- 



mis ; intus albd, marginibus crenatis ; epiderm 

 fused, villosd. 



The spotted Pectunculus. Shell orbicular, sligh 

 eared, nearly equilateral, convex, whitish, spot 

 with chestnut, somewhat decussated with thick- 

 radiating striae ; interior white, margins crenatf 

 epidermis brown and downy. 



Broderip, Proc. Zool. Soc, 1832, p. 126. 



Hub. Puerto Potrero, Central America. Cuming. 



The spots which peculiarly characterise this si 

 vary in different individuals, the colouring matter, as 

 most of the Pectunculi, being very sparingly secreted 

 an advanced stage of growth. 



