24 s G. O. Sårs. 



III. Adult form. 



(Pl. VI, figs. 3 & 4). 



The full-grown animal of both sexes has been described 

 in detail by the author in his previous paper, from alcoholic 

 specimens. I shall therefore here only give some notes on the 

 colouring and the habits of the animal, as observed in my 

 aquaria, and add 2 figures of the largest specimen reared, 

 representing the animal within its shell viewed from the side 

 and from above, in the attitude it generally assumes when 

 brought under the microscope in a suitable quantity of water. 



The specimen, which was of the female sex, measured in 

 length about 7 mm., and may be supposed to have attained 

 its full size, as the lines of growth were no less than 24 on 

 each valve, or as many as in the largest specimen formerly 

 examined. The shell was horn-coloured and semi-transparent, 

 whereas the enclosed animal exhibited a very dark brownish 

 red colour, turning, on the ventral face and on the legs, to a 

 vivid and deep blood-red. The alimentary canal could be only 

 faintly traced through the shell, and on its sides the greatly 

 developed, opaque whitish ovaria could be discerned, in the 

 form of elongated, twisted bags (see fig. 3). 



As to habits, the animal showed itself to be on the 

 whole rather sluggish, being often found for a rather long 

 time resting on the very same place, more or less deeply 

 burried within the loose bottom deposit. At times, however, 

 and especially in clear weather, it made some abrupt ex- 

 cursions through the water, moving rather rapidly, and at a 

 perfectly even rate up along the Avails of the aquarium, some- 

 times up to the surface of the water; but it very soon sank 

 back to the bottom, assuming again its quiet attitude. The 

 movements, as in other bivalvePhyllopoda, seem to be exclusively 



