Dr. E. F. Kelaart on new species of Ceylonese Mollusca. 495 



sionally buries itself in sand^ with only the head and tentacles 

 exposed, and lies for hours in this position. 



Order TECTIBRANCHIATA. 



Animal usually provided with a shell both in the larva and 

 adult state. Branchiae covered by the shell or mantle. Sexes 

 united. 



Fam. PleurobrancMdae. 

 Genus Pleurobranchus, Cuv. 



Animal oblong, fleshy, convex above, with a very large and over- 

 spreading mantle. Foot large, equally outspreading, and 

 thus leaving a wide canal all round the body. Head distinct, 

 furnished with a veil, uniting on each side with the borders 

 of the foot, and with tw'o tubular tentacles, which are split 

 anteriorly ; mouth at the extremity of a proboscis. Branchiae 

 composed of a double row of lamella, forming a plume on the 

 posterior right side, between the mantle and the foot. Anus 

 carried by a small tube behind the branchire. Organs of 

 generation in front. Shell sometimes rudimentary, mem- 

 branous, with a tolerably distinct apex hidden in the thick- 

 ness of the mantle. — Woodward. 



Pleurobranchus citrinus ?, Riippell. 



Orange-red. ]\Iantle darker than the other parts of the animal, 

 and speckled with whitish spots. About 1 inch in length. 

 Ova reddish, in circular broad coils. 



Very common in Trincomalee. Found at low-water, on coral 

 stones and sea-weed, nearly throughout the year. Spawns in 

 May, June, and July. 



Pleurobranchus reticulatus ?, Gmel. 



Pale orange-red, reticulated mantle, and spotted with purple. 

 About 2 inches long. 



Found near Fort Frederick, Trincomalee, in shallow water, 

 among rocks. 



Pleurobranchus zeylanicus, Kel. 



Pale yellow, splashed with darker yellow and brown, and mi- 

 nutely spotted with rusty brown. About 2 inches long. 

 Rare; found in Back Bay. 



Pleurobranchus purpureus, Kel. 

 Deep reddish purple. Mantle very dark purple, and spotted 



