2(50 CEYLON PEARL OYSTER REPORT. 



A much smaller complete specimen from the same locality is also contained in the 

 collection and shows to perfection a feature which is present in the larger individual. 

 The anterior setae of the buccal segment are exceedingly long and slender, as long as 

 the tentaculum and tentacular cirri, and they embrace these appendages in such a 

 manner that the whole complex bears the appearance of a compact flabellum. 



There is a great quantity of mucus surrounding the specimens which was 

 apparently produced by the Glycerids with which they were preserved, and this no 

 doubt binds the setae and tentacles fortuitously together, but the extremely delicate 

 porrect fascicles of long hair-like setae are highly characteristic. Another point which 

 should be noted is the greater length of the appendices of the compound setae in the 

 anterior segments. In the smaller specimen there are fewer spinulose or verticillate 

 setae in the superior fascicle of the ventral ramus, and the stylodes appear to be less 

 numerous ; in fact, in a parapodium from the mid-body I only see one verticillate seta 

 as in Leanira japonica, McInt. Although the Japanese worm retained no scales, 

 yet it seems probable that the Ceylon specimens are co- specific. In these the scales 

 adhere firmly to the body. 



Thalenessa digitata, McIntosh Plate II., figs. 50 to 52. 



Thalenessa digitata, McIntosh, " Polychoeta," '"Challenger" Rep.,' 1885, p. 140 (off the 



Admiralty Islands in 16-25 fathoms). 

 Thalenessa im-tlnirni, Hornell, ' Ceylon Pearl Oyster Report,' Part I., 1903, pp. 16, 49, and 52. 



Taken off Galle (Station XXXVIII.) and off Panadure (Station XLV.) down to 

 25 fathoms. 



Three small frontal antennae ; the lips of the anterior four pairs of setigerous 

 parapodia are produced into conspicuous membranellai and also carry numerous 

 stylodes ; the first five setigers contain setae with long, jointed appendices, such setae 

 being numerous in the first four feet, scarce in the fifth, and thereafter absent, only 

 setae with unjointed appendices being found (Plate II., fig. 50). All these points 

 correspond closely with Professor McIntosh's description and figures. 



The elytra do not cover the back ; the first two elytra are smaller than the rest, 

 and the first has a smooth margin, destitute of fimbriae ; a typical elytron is sub- 

 triangular in shape, the outer border provided with about a dozen compound fimbriae, 

 more frequently with four divisions each (Plate II., fig. 51), but there may be as 

 many as six branches, or only three, two, or one. The elytra are attached to seg- 

 ments II., IV., V, VII. , IX., ****** * XXV, XXVII. , XXVIII. , 

 XXIX., &c, becoming continuous at segment XXVII. Cirriform branchiae are 

 present in all setigerous segments, two clear ctenidia on the dorsal surface of the foot, 

 one attached to the peduncle of the gill. Ventral cirrus long, projecting beyond the 

 foot. No papillae on the ventral division of a typical foot from the middle region. 



Tlmlenessa oculata, McIntosh, is apparently another form of digitata, slightly 

 differing from the type. It is interesting to take note of the differential shifting of 



