GASTEROPODES. 299 
Srcron III. Eoris—In the dismemberment of the genus Doris by 
recent naturalists, they have left a place for a very large section, under 
the name of Lolis. 
But, so many novelties, varieties, and difficulties, continually occur 
to the practical naturalist attempting a systematic arrangement of such a 
numerous tribe as the Doris, as taken in its original signification and 
more comprehensive sense, that he will even find himself compelled to 
modify his general plans on a retrospect. He cannot discover such spe- 
cific, exclusive, and permanent characteristics, as enable him to assume 
with confidence the exact principles laid down for his guidance, and, in 
general, he will find that instead of including the great field of Nature, 
they embrace but the narrowest portions of it. 
Thus, we cannot yet admit the detail proposed by some systematic 
authors to be irrevocably settled. It is still open to alteration. 
Though having had a multitude of specimens of the different families 
in my possession, as many, perhaps, as would have induced more skilful 
observers to frame several genera from them, I can never take a retro- 
spect of the subject without distrust, so much had to be seen amidst the 
little that was disclosed. Therefore, instead of classing certain members 
in determinate series, I shall dono more than give a general description, 
and suggest how they may be united, from some of their most prominent 
features. The accompanying figures may contribute assistance. 
The preceding sections comprehend such animals as may be gene- 
rally discriminated with tolerable facility. Perhaps the whole to be in- 
cluded here are not alike definite. 
Eouts.—Tentacula two, prolonged from the head. Cornicula two, 
rising from the neck, without sockets. Back partly bare. Branchiz 
commonly formed as elongated papilla, tapering or enlarging from their 
origin on the upper surface, single or disposed in groups or clusters. 
