410 Mr. W. H. Benson on Ianthina, Bolten. 
increasing whorls of the true species. The chief character of the 
“ discoid” I. planispirata consists, according to the original de- 
scription, in “its narrow depressed mode of convolution,” of 
which Reeve’s figure No. 9 exhibits no appearance, the body of 
the shell in the latter exceeding in magnitude the area of the 
aperture, whereas in the ‘Samarang’ figure the aperture is larger 
than the body of the shell. Mérch refers Reeve’s figure to J. 
planispirata as “ var. y. grandis,” without further remark. 
A. Adams says nothing of the sculpture. All my specimens 
are sculptured with undulate and radiate striz, which are more 
closely packed and more sharply plicate on the basal portion. 
Morch refers I. planispirata to the subgenus Jodes, Leach, the 
animal of which is stated to be viviparous. 
I, fragilis, Lam. (including the variety I. affinis, Reeve). 
The violet colour of the under side of the shell was visible in 
the water through the float, and assisted to distinguish it from 
the foam. The float was of strong texture, and was composed of 
large transverse polyhedrous globules arranged in a convex form 
on the surface exposed to the air; one proved to be dichotomous, 
evidently from some accident. The cilia within the animal’s 
mouth were stiff and prickly. Mdérch includes the species in 
the subgenus Achates, Gistel, recorded as being oviparous. Our 
specimens were destitute of ovisacs ; whether in consequence of 
the season for their reaching maturity having passed, and of the 
animals having provided themselves with fresh floats, or from ~ 
their being permanently deficient in those appendages, cannot 
be asserted. As soon as the water in which the specimens were 
placed for examination was changed, a quantity of beautiful car- 
mine fluid ejected spoiled it, and all died on the following day, 
some of them casting off their shells, when the animal, including 
the spiral portion, remained attached to the float at the surface 
of the water. A gummy coat, which was easily rubbed off while 
the shell was wet, dried into a moderately polished surface. 
The dimensions of four examples are as follow, tending to 
corroborate Morch’s suggestion regarding J. affinis, Reeve :— 
Long. . 
Specimen resembling J. affnis 224 254 mill. 
Approximate form . . . . 21° 26°; 
Depressed variety’. s,s 19 Bane 
Smallest specimen . . . . 17% 20 ,, 
The last approaches in form Rang’s figure, which Morch refers, 
as a variety, to I. violacea, Bolten. - 
Respecting the younger examples of the variety taken in the 
Bay of Bengal, I only noted the number of individuals captured. 
j 
