DORIS. 107 
The upper or dorsal tentacles are generally short 
club-shaped organs, with the upper portion fre- 
quently bent into an angle. This 
portion is always set with narrow, 
oblique plates, usually ten or 
twelve in number, pointing be- 
hind and downward. They are 
always retractile, but for the most 
part not sheathed. 
The species of this genus de- 
posit their spawn in the spring ; 
the eggs, as already described, 
being generally arranged intrans- 
verse rows, imbedded in a trans- 
parent gelatinous ribbon. Doris 
bilamellata, which I have kept 
in captivity, always deposited 
its ribbons on the side of the 
vessel just beneath the surface of the water. It 
adheres by one edge, and forms an imperfect spire 
or cup, the ribbon being bent upon itself, the upper 
edge or brim leaning a little outward, and being 
puckered. That of D. tuberculata is very large, the 
ribbon being three-fourths of an inch high, and 
wound round in many spiral coils. I have observed 
it, on the Devonshire shores, depending in a flaccid 
manner from the under surface of rocks, durimg 
the recess of the tide. The embryos in such coils 
of spawn are immensely numerous. Mr. Darwin 
thus describes the contents of a spawn-coil of a 
species of this genus, which he found at the 
Falkland Isles. ‘‘ From two to five eggs [yolks], 
each 75pths of an inch in diameter, were con- 
tained in a spherical little case [chorion]. These 
were arranged, two deep, in_ transverse rows, 
TENTACLE OF DORIS. 
