GASTEROPODES. 293 
They came into mutual contact, as they were seen tumbling over each 
other. The integument of the capsule must be inconceivably thin, from 
its transparency. It is doubtful whether, of these four Nautilines con- 
tained in a capsule referred to, each is confined in its own peculiar inte- 
gument.—Plate XLIII. fig. 7. 
This great deposit, obtained on the 12th of February, was chiefly 
dissolved and broke up on the Ist of March ; and numbers of the Nauti- 
lines were observed floating at the surface of the water. 
All this was of no avail, however, in determining whether the spawn 
had been produced by the argo or verrucosa; though the subjects afford 
good illustrations of the general nature of the Doris. 
It is not easy to obtain a satisfactory microscopical view of the com- 
position of the prolific ribband, and it would be vain to attempt computing 
the multitude of the offspring from a single individual. 
The propagation of this animal is not confined to any particular 
season, though more common in the earlier part of the year. Vast 
numbers of young have been matured from spawn produced in March. 
Multitudes of the Nautiline formed a whitish scum on the surface of the 
water of a vessel, which, exposed to the microscope, proved partly those 
creatures, partly their empty shells. It should be understood, that the 
shells are simple cavities ; they contain neither chambers nor partitions. 
When occupied, the animal appears wholly grey, with several internal 
sacs or solid organs ; also a transparent vessel, of considerable size, con- 
taining a colourless fluid, wherein dark globules are suspended and car- 
ried about, as if around the interior circumference. All Nautilines exhibit 
two external circular spots, apart, on the middle of the front, which cer- 
tainly denotes two organs in the earliest stage. 
Although this be the most common of the tribe, often dwelling little 
within low water-mark, and occurring of very small dimensions, I have 
never met with it, or with any other so minute, or of such form, as would 
indicate transition from the Nautiline. Perhaps it feeds on the alge and 
the fuci. It is of the most sluggish nature, and actually becomes agelu- 
tinated at last to the surface whereon it reposes. 
This species is prone to quit the water. 
