60 SPOLIA ZEYLANICA. 



H. marmorata found at Trincomalee, as I have examined 

 hundreds of Hving specimens. The presence of a local race 

 would, however, account for the constancy of this colour in the 

 comparatively small area of Trincomalee Harbour. I cannot 

 vouch for the constancy of the colour of the other two species, 

 but I have not discovered any form having markings inter- 

 mediate between the characteristic " circles " oi H. argus and 

 the irregular markings of H. vitiensis, nor has any other 

 observer. An examination of the internal organs does not 

 help much. It is true that I have found slight differences 

 between the apparently similar calcareous rings of the three 

 species, but I am quite jorej^ared to find these differences break 

 down upon an examination of a larger series. At first sight 

 the spicules of the three forms are indistinguishable, but 

 H. marmorata possesses calcareous grains in the deeper 

 integument which are absent from the other two. This, then, 

 clearly separates H. marmorata from H. argus and H. vitiensis. 

 Sluiter (39) finds very little difference between the two latter 

 species, except the thicker skin of H. argus. But apart from 

 colour differences the pedicels show a difference in regard to 

 the supporting spicules, H. argus having large supporting rods 

 which are not present in H. vitiensis. 



I give below a short key to distinguish the three species : — 



A. — Small spherical spicules in the hypodermis. 



H. marmorata. 



B. — Spicules absent from the hypodermis — 



(a) Dorsal surface conspicuously marked with 



circular patches. Spicules of pedicels, long 

 bars with perforated ends 200 [jl long, and 

 smaller irregular often H-shaj^ed spicules 

 40 tx long. 

 H. argus. 



(b) Dorsal surface not possessing numerous circles. 



Spicules of pedicels consisting of rods 75 ^ long 

 and irregular H-shaped spicules 40 [j. long. 



,j , ^ H. vitiensis 



