324 CEYLON PEAEL OYSTER REPORT. 



collection, one comes upon specimens showing this opaque dull bluish-grey appearance, 

 there is at least a strong probability that the colour in life was red. I have pleasure 

 in dedicating this interesting little species to my friend Dr. A. J. Chalmers, Professor 

 in the Medical College at Colombo. 



Polycarpa alentura, n. sp. Plate V., figs. 33 to 37. 



External Appearance. Body conical or dome-shaped (fig. 33), attached by a broad 

 base at the posterior end. Apertures on the narrow anterior end, not projecting, 

 inconspicuous. Colour, yellowish grey ; size, 2 centims. x 1 "5 centims. 



Test smooth, slightly wrinkled, leathery. 



Mantle thin, pigmented, having a very fine felting of delicate muscle fibres. 



Branchial Sac with four wide folds on each side, about 15 internal bars on a fold, 

 and about seven rows of meshes in the interspace. Transverse vessels of several sizes ; 

 meshes narrow, containing three to five stigmata each (fig. 37) ; the stigmata are 

 crossed by a narrow horizontal membrane. 



Dorsal Lamina with a few slight denticulations at the anterior end (fig. 35). 

 behind that a plain membrane. 



Tentacles rather short and irregular, 14 in number, differing a little in size. 



Dorsal Tubercle curiously shaped (fig. 36) with the aperture posterior, one end 

 turned in and the other out. 



Alimentary Canal with a widely open intestinal loop ; stomach yellow-brown, 

 striated longitudinally (fig. 34). 



Gonads consisting of a few polycarps only. Large numbers of small endocarps 

 engorged with opaque yellow blood corpuscles project from the body-wall. 



Locality : Statiou LVIIL, off Alentura Paar, 9 to 26 fathoms, one specimen. 



Polycarpa decipiens, n. sp. Plate VI., figs. 33 to 39. 



External Appearance. Body rounded and covered with sand like a Molgula, 

 unattached. Both siphons on the anterior end, but rather distant (fig. 33) ; size, 

 about 1 centim. across. 



Test thin, but covered with a soft, rather loose, coating of sand. 



Mantle thin and transparent. 



Branchial Sac with four slight folds on each side (fig. 34). Each fold has only 

 three or four internal bars, and there are no bars in the interspaces. Between the 

 endostyle and the 1st fold are 16 stigmata, between the 1st and 2nd 8, between the 

 2nd and 3rd 8, between the 3rd and 4th 10, and between the 4th and the dorsal 

 lamina 14. The stigmata are shown in fig. 35. 



The Dorsal Lamina is a plain membrane. 



The Tentacles are about 20 large, not all quite the same size, and intermediate very 

 much smaller ones. 



