350 CEYLON PEARL OYSTER REPORT. 



small black spots, about 1 millim. in diameter, scattered over the surface of the body. 

 The amount of pigment on the inner side of the pleuropodia varies ; usually there is 

 very little, and it is almost absent in some specimens. 



The length of a well-preserved specimen was 6 "3 centims. The pleuropodia were 

 free to within from 5 millims. to 8 millims from the end of the foot. The excurrent 

 mantle siphon was moderately produced, from 5 millims. to 10 millims. in length. 

 The tentacle flaps were mostly flattened, but varied according to the amount of 

 contraction. The mantle foramen was closed in some specimens, but the mark of its 

 position was apparent ; in others it was about 2 millims. in diameter. The markings 

 and clear spots showed a sort of radial arrangement round the foramen. The hyaline 

 gland (Plate IV., fig. 6) consisted of a group of large globular cells lying beneath the 

 sub-dermal muscle layer and penetrating it at intervals. There was no sign of 

 a single common duct. The gland in appearance resembled a bunch of grapes 

 attached laterally to the muscle layer, and would seem to be intermediate in form 

 between the two types of gland described by Blochmann (6) as occurring in Aplysia, 

 since the cells appeared to open separately on the surface or else two or three into a 

 common opening. 



The shell (Plate IV., fig. 4) is thin, with a fragile calcareous layer; the inside is 

 opalescent, of a delicate pale pink tint ; the outside is glossy, pale whitish-brown, with 

 distant growth ridges. 



The radula (Plate IV., figs. 2, 3, 5) consists of about 40 rows of 21-1-21 teeth ot 

 the usual form ; the 16th and 17th from the centre have rudimentary hooks and the 

 four outermost teeth consist of flat plates. The labial armature is made up of 

 blunt rods. 



A. pulmonica, Gould, from Samoa, may perhaps prove to be the same as this 

 species, but seems to be separated by having the pleuropodia fused for a larger 

 proportion of their length. 



Aplysia elongata, Pease Plate IV., figs. 9 to 12. 



A specimen of the above was taken on Jokkenpiddi Paar in April, 1902. 



The length of the preserved specimen is 1"2 centims., height 9 centim. The 

 colour is an opaque whitish fawn with brownish markings irregularly arranged, 

 leaving vacant spots, and in addition a fairly uniform but rather distant spotting of 

 opaque white pigment. The eyes are distinctly visible, the skin over them being 

 devoid of pigment. They lie lateral to and a short distance from the base of the 

 rhinophores. The rhinophores (Plate IV., fig. 10) are tubular and split for about 

 f of their length ; they resemble greatly a hare's ear in appearance. The tentacles 

 are much shorter than the rhinophores and are split to the base. The inside of both 

 rhinophores and tentacles is strongly pigmented. The pleuropodial lobes are short, 

 meeting behind the mantle siphon ; they are slightly pigmented with light brown on 

 the inside. The mantle is transparent and colourless except for a black line along 



