OPISTHOBEANCHIATE MOLLUSCA. 



of mantle over gill paler, with edging of violet." In the spirit specimen the markings 

 are as described, but the blue and green colours have disappeared ; the ground colour 

 is a pale brown. 



The length of this specimen is 1'45 centims., width 1'05 centims., length of head 

 shield 0'9 centim., width 0'85 centim. The shell was very much broken. The foot 

 is pale, without markings, its margins are only slightly incurved. 



There is nothing in the form of the animal to separate it from D. depictum of the 

 Mediterranean, and, as that species is known to be extremely variable as regards 

 coloration, I have recorded the Ceylon specimen as a variety. 



FAMILY: APLYSIID^. 



There appears to be a great amount of uncertainty as to the extent of the genera 

 Dolabrifera, Aplysiella and Phyllaplysia, each author using the names with a 

 different meaning. The distinctions have been based mainly on the form of the animal, 

 which must vary considerably in the same species in preserved specimens. I have 

 not material sufficient to throw any light on the matter, and have for convenience 

 merely used the names in the following manner : 



Aplysiella. Specimens with short median mantle slit, swollen body and 



broad foot. 

 Phyllaplysia. Specimens with depressed body, median mantle slit and broad 



foot ; shell in this and the preceding genus resembles that of Aplysia. 

 Dolabrifera. Specimens with moderately depressed body, broad foot, posterior 



mantle slit and bat-shaped shell. 



The circum-oesophageal nerve ring shows the same type in all, the commissures 

 being short, the cerebro-pedal being almost as long as the cerebro-visceral. In 

 the two species of Dolabrifera which occur in the collection there is a resemblance in 

 the radulas in the fact that the inner cusp of the lateral teeth is always smaller than 

 the outer. 



Aplysia cornigera, Sow. Plate IV., figs. 2 to 7. 



It is impossible, on account of the many vague descriptions, with or without 

 figures, which have been published, to say with certainty what name should be 

 applied to what appears to be the common Ceylon species of Aplysia. I have 

 identified it as A. cornigera, Sow, on account of the resemblance to the shell of that 

 species, of which only the shell is known. It is represented in the collection by 

 seven specimens, two from the Gulf of Manaar, two from the pearl banks off Aripu, 

 one from the pearl banks off Manaar and two without definite locality. 



The coloration of these specimens is a groundwork of fine reticulating brownish- 

 olive lines, with clear spaces here and there, as in A. punctata, There are also 



