INDIAN NUDIBRANCHIATE MOLLUSCA. 115 



of calcareous spicula', a characteristic hitherto supposed to have been universal in the 

 Acanthobranchiata (those animals, namely, that have the branchiae 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 Mandihulata (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, Cuvier. 



Suborder Acanthobranchiata, Fhussac. 

 Family DORIDID^, Alder £f 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. 

 'I'his 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 m spirit, which, Uke all the other specimens, is without 

 spicula. 



2 Another apparently new genus is figured in the plates, but sufficient materials have not been preserved for 

 its description. 



