316 CEYLON PEARL OYSTER REPORT. 



Mantle thin, transparent and very slightly muscular, except on the two short 

 siphons, where there are strong sphincters. 



Branchial Sac with four slight hut well-formed folds on each side. About six bars 

 on a fold, and four to six rows of meshes in the wide interspaces (fig. 14). The meshes 

 are square, contain each about five rather large closely placed regular stigmata,, and 

 are divided horizontally by a membrane. Narrower and wider transverse vessels 

 alternate. 



Dwsal Lamina is a corrugated membrane. 



Tentacles of three sizes (fig. 15), eight of the largest, eight of the second, and 

 sixteen of the smallest. 



Dorsal Tubercle with a simple but wide funnel-shaped opening (fig. 15). Peri- 

 tubercular area narrow. 



Alimentary Canal with a wide intestinal loop (fig. 10) ; stomach ridged. 



Gonads a curved, slightly lobed organ on each side of the body, having the ovary 

 along the middle and the spermatic casca on the edges. 



Localities : (1) Stations LIII. and LIV., in north part of Gulf of Manaar, 4 to 40 

 fathoms, a few specimens; (2) Station XLVL, off Mount Lavinia, 30 fathoms, four 

 specimens; (3) Station XXIV., Outer Bay, Trincomalee, 24 to 4G fathoms, a dozen 

 specimens; (4) Station XLIX., South Periya Paar, 13 fathoms, eight specimens; 

 (5) Station LXIIL, West of Periya Paar, 17 to 55 fathoms, nine specimens. 



This seems to be a common species around Ceylon, as a number of specimens were 

 found at localities on both sides of the island. 



The appearance of the tentacles and of the dorsal tubercle (fig. 15) is very 

 suggestive of a Polystyelid or a Botryllid. 



The apertures are striped with yellow and red when alive. The stiff' brittle sandy 

 test and the large curved gonad on each side are characteristic features. 



Styela areolata, Heller Plate IV., figs. 24 to 33. 



It is necessary to re-describe this species, with figures, since Heller's description 

 was very brief and no illustrations have been published showing the structure. 



External Appearance. Body ovate, attached by a few slight tag-like processes at 

 the posterior end. Siphons slight, both on dorsal edge, ajjertures small, cross-slit. 

 Surface uneven, but smooth. Colour, milky white. A little sand adhering towards 

 the posterior end (fig. 24). Size about 2 centims. x 1"5 centims. 



Test thin and semi-transparent, smooth on the surface except where encrusted with 

 sand. The test may be reduced to a very thin layer in the middle of the posterior 

 end, and has thickened edges round the area of attachment. There are vessels in 

 the test. 



Mantle semi-transparent, allowing the viscera to show through. The muscle 

 bundles are very fine. 



