GASTEROPODES. 283 
receptacle for the tentacular or sensitive portion, which resembles a fir 
cone. Five or six pair, or more, of palmate branchive rise from the mar- 
gin of the back, 4, the number and dimensions depending on the age and 
size of the specimen. Towards the posterior extremity, these gradually 
shorten and simplify in structure, and at length degenerate into mere 
prominences. Several organic prolongations, besides, of different charac- 
ter, likewise issue from the anterior part. The orifice of the oviduct 
opens under the right of the branchia of the first pair. 
The whole upper surface of the animal presents a tuberculated as- 
pect, which is certainly heightened by the variegation and interspersion 
of colours, sometimes exhibiting delusive appearances. ; 
Plain or mottled brown predominates in the colour of the Stag-horn 
Doris ; sometimes with white extremities. Small sized live specimens, 
of dingy white, have occurred. One, perfectly white, an inch and a half 
long, but scarcely surviving, seemed of the same species. In such light- 
coloured specimens, especially if young, ocular specks may be occasionally 
recognized behind the roots of the cornicula. Besides more obscure ex- 
amples, a white patch with a black speck appeared at the exterior basis 
of each corniculum, in a small specimen. But observations on this sub- 
ject have not been satisfactory.—The pulsation of the heart, in favour- 
able specimens, is very distinct, the great dilatation being backwards, as 
a circular segment, below the first pair of branchiz. On favourable oc- 
casions, also, two marginal channels, running along the back, may be dis- 
covered, penetrating the roots of the branchise, from whence they are 
distributed towards the extremities. 
The union of these animals has been witnessed in October. It was 
once followed in two days by spawn. On the same day, another union 
ensued, both animals being much reduced in size, as is always concomi- 
tant on breeding. 
The spawn consisted of two portions, each a waving rope in a loga- 
rithmic curve. The larger, composed of three coils or volutions, was the 
sixth of an inch in diameter, the ova pure white.—Plate XL. figs. 8, 9, 
enlarged. 
The young having come to maturity in twelve days, escaped in the 
