354 CEYLON PEARL OYSTER REPORT. 



The labial armature is made up of bluut rods. 



This species may perhaps prove to be identical with one of the many forms 

 described by Pease from the South Pacific (3), (4). 



Dolabrifera marginata, n. sp. Plate V., figs. 11 to 15. 



One specimen dredged on South Cheval Paar. 



The length of the preserved specimen is 1*95 centims., width 1*3 centims., height 

 075 centim. The form of the body is ovate, somewhat narrower in front, the body 

 passing into the head without a distinct neck (Plate V., fig. 11). The branchial slit 

 is situated far back, about 4 millims. from the posterior end of the body. The slit 

 is 7 millims. in length, open at both ends, the right pleuropodial margin being lapped 

 over the left in the centre. The genital furrow is well marked. The margin of the 

 foot extends beyond the body laterally and posteriorly, forming a frill 1*5 millims. 

 wide. The body is smooth, the skin being somewhat tense. The rhinophores and 

 tentacles are short, tubular, and slit as usual. The eyes are visible in front of the 

 rhinophores. 



The shell (Plate V., fig. 15) is very thin and membranous, of the same form as in 

 D. maillardi, but perfectly transparent except for a chalky powder over parts of its 

 surface which rubs oft' at a touch. The apex of the shell was injured in extraction, 

 so it could not be ascertained whether an embryonic spine was present or not. It is 

 probable that this species has not been already described, as the shell is not well 

 fitted for preservation in a conchological cabinet. 



The radula (Plate V., figs. 12, 13, 14) is of the same type as in D. maillardi, but 

 the lateral teeth are not so slender. It consists of 37 rows of 57-1-57 teeth. 



Dolabella scapula, Mart. Plate V., figs. 16 and 17. 



There are three specimens of this, the common species of Dolabella of the Indian 

 Ocean ; one from South-east Modragam and two from south of Adam's Bridge. 



The coloration of the preserved specimens consists in a faded yellowish-white 

 ground colour mottled over the body and foot with irregular olive-brown blotches. 

 Professor Herdm an notes of another specimen from S. of Cheval, 6|- fathoms : ' ' Chestnut 

 brown in general effect, yellowish basis mottled with red and brown, many yellow 

 tags or spines all over, broad flat foot rather paler." In the preserved specimens the 

 body was covered sparsely with short fringed papilla?, longest on the margin of the 

 posterior disc. These papillae were most numerous in the largest specimen, which 

 measured 4*8 centims. in length, and almost absent from the smallest. 



Some of the published descriptions state that D. scapula is uniformly coloured, 

 but this is probably a matter of individual variation. The shell of the Ceylon 

 specimens agrees with that of D. scapula, having kindly been compared with 

 specimens in the British Museum by Messrs. E. A.. Smith and E. R. Sykes. 



The radula consists of 44 rows of about 120-1-120 teeth, those near the centre 



