318 CEYLON PEARL OYSTER REPORT. 



third of the way back. Both apertures very regularly four-lobed (fig. 28). Colour, 

 grey. Size, 2*5 eentims. x 1 ceutim. 



Test cartilaginous, full of bladder cells (tig. 30) and pigment cells (blue, black, red 

 and yellow). 



Mantle bavins' a fine network of fibres running in all directions. 



Branchial Sac large and loosely disposed, with four folds on each side. Transverse 

 vessels rather wide, of tbree sizes. Internal bars wide, ribbon-like ; from eight to 

 sixteen on a fold and six to eight in the interspace. Meshes square, containing each 

 four or five stigmata (fig. 32). 



Tentacles large and closely placed, about 30 (fig. 31). 



Dorsal Lamina a plain membrane. 



Dorsal Tubercle small and inconspicuous, placed close to the tentacles (fig. 31). 



Nerve Ganglion and neural gland forming a conspicuous spot. 



Alimentary Canal forming a narrow loop at posterior end of left side (fig. 29) ; 

 stomach simple, ovate. 



Gonads nine prominent yellow masses on each side, closely packed, pyriform, with 

 ducts directed towards the atrial aperture. 



Locality : Station LVIIL, Alentura Paar, Gulf of Manaar, 9 to 26 fathoms. 



The cartilaginous test, with its Ascidia-like structure, and the minute dorsal 

 tubercle placed close to the tentacles, are special features of this species. 



Styela piginentata, n. sp. Plate VI., figs. 24 to 26. 



External Appearance . Of quadrate shape, broader than long, attached by a wide 

 base (fig. 24); somewhat encrusted and covered with growths of weed, &c, but not 

 stiff. Colour dark ; size, about 3 eentims. x 3 eentims. 



Test leathery, but rather soft and flexible, with Crenella embedded in its thickness ; 

 yellowish grey and glistening on the inside. 



Mantle soft, and opaque dark brown ; not muscular ; inner surface pigmented 

 vellow and white. 



J 



Branchial Sac pigmented with yellow and white, with four well-marked folds on 

 each side. There are at least six internal bars on a fold and three in the interspace. 

 The meshes contain each eight stigmata (fig. 25). 



Endostyle with very wide, white pigmented lips. 



Dorsal Lamina a plain membrane. 



Tentacles pigmented yellow and white. 



Dorsal Tubercle represented by a diffused triangular area covered with minute 

 pores (fig. 26). 



Locality : Jokkenpiddi Paar, Gulf of Manaar, 8i to 10 fathoms. 



Polycarpa aurata, Quoy and Gaimard Plate V., figs. 1 to 6. 

 External Appearance. Shape oblong, erect, with both apertures at anterior end, 

 sessile, not distant (fig. 1). Attached by posterior end, and having a little encrusting 



