INDIAN NUDIBRANCHIATE MOLLUSCA. 1 
of calcareous spicula’, a characteristic hitherto supposed to have been universal in the 
Acanthobranchiata (those animals, namely, that have the branchie surrounding the 
vent on the central line of the back). This new genus, which we have named Doridopsis, 
cannot be distinguished from Doris by any external characters, if we except the small 
size of the head and mouth, and a remarkable difference in the position of the latter. 
The structure of their buccal apparatus, however, indicates as great a difference in the 
economy of the animals as exists between the Haustellata and Mandibulata (suckers 
and masticators) among insects, though we have not in this case considered the divi- 
sions entitled to so high a rank. 
The Goniodoris of Forbes has hitherto been considered a northern form—the southern 
species which some authors have referred to it belonging almost without exception to 
the allied genus Chromodoris, which, on the other hand, has not been found further north 
than the Mediterranean. In this collection, however, three species of the true Gonio- 
doris appear, while only one of the Chromodoris is present. Most of the genera belong- 
ing to other families are distinct from those of Europe. A few Eolides are found; but 
their numbers are proportionally small, compared with those of northern latitudes. 
Three only occur in this collection ; and seven others are described by Kelaart. As these 
collections have been made with care, they probably represent pretty fairly the predo- 
minant characters of the Indian Nudibranchiate fauna. 
In all, there are four new genera in the collection*, which comprises forty-two species, 
thirty being undescribed. 
Order NUDIBRANCHIATA, Cuwvier. 
Suborder ACANTHOBRANCHIATA, Férussac. 
Family DORIDIDA, Alder & Hancock. 
Cloak large, spiculose, without marginal appendages. Dorsal tentacles retractile 
within cavities. Oral tentacles various or wanting. Mouth with a denticulated pre- 
hensile tongue, and occasionally with a spinous collar. 
' Mr. Elliot’s specimens had unfortunately been preserved in some saline fluid, which, in most cases, 
had injured the spicula to such an extent that they could not be made out satisfactorily ; moreover it had 
rendered many of the specimens hard and brittle, so that they were quite unfit for anatomical examination, 
This must account for the imperfect descriptions of the spicula, and some other deficiencies, that will be found in 
the following pages. We can, however, speak pretty confidently to the absence of spicula in Doridopsis, as 
Kelaart’s collection, which is preserved in spirit, contains several species of this new form; and we have in our 
possession an individual of this genus from Madeira, also in spirit, which, like all the other specimens, is without 
spicula. 
? Another apparently new genus is figured in the plates, but sufficient materials have not been preserved for 
its description. 
