BRITISH NUDIBRANCHIATE MOLLUSCA. 



XVI 1 



d. Dorsal tentacles linear ; oral tentacles angular, flattened. 

 Lingual spines denticulated ; a small central spine. Mouth 

 with a spinous collar 



e. Dorsal tentacles conical, partially retractile, and pro- 

 tected by leaf-like appendages ; oral tentacles linear or 

 tubercular ; branchiae linear, simply pinnate ; cloak with 

 large tubercles. Lingual spines simple, uniform ; no central 

 spine. Glossodoris, Ehr. 



f Dorsal tentacles conical ; oral tentacles leaf-shaped ; 

 branchiae each with several pinnate rays branching from 

 a footstalk ; cloak very large, fiat, and coriaceous. Lingual 

 spines? Actinodoris, Ehr. . 



g. ? With only two tentacles; branchiae in front of the anus, 

 not surrounding it. Lingual spines? Actinocyclus, 

 Ehr. ..... 



h. ? Dorsal tentacles truncated ; branchiae small ; cloak large, 



carinated on the back. Lingual spines ? Atagema, Gray. 



Gen. 2. Chromodoris, A. and H. Body subquadrilateral ; cloak narrow, 



exposing the foot, smooth; dorsal tentacles laminated, 



retractile within plain or raarginated cavities ; oral tentacles 



conical or tubercular; branchiae linear, simply pinnate, 



retractile ? Tongue ? ... 



Gen. 3. Lamellidoris, A. and H. Body depressed; cloak large; dorsal 



tentacles laminated ; head with a veil ; no oral tentacles ; 



branchiae simply pinnate, set in an open circle, non-retractile. 



Tongue narrow, with few spines. 



a. Body not greatly depressed ; cloak with moderate-sized 

 spicula; spawn of few coils, cup-formed. Tongue with 

 2 large spines and 2 or more rudimentary ones ; usually 

 a simple central plate 



b. Body very flat, with large spicula, symmetrically 

 arranged ; spawn of many narrow coils. Tongue ivith 

 2 large broad spines and 2 rudimentary ones • no central 

 plate .... 



Gen. 4. Hexabranchus, Ehr. Cloak very large and flat, with an undu- 

 lating margin ; dorsal tentacles laminated, kneed, retractile 

 within marginated cavities ; oral tentacles large, ovate, with 

 scalloped edges ; branchiae generally in 6 tufts, set separately 

 round the vent and non-retractile. Tongue ? 



Gen. 5. Acanthodoris, Gray. Body convex; cloak with soft conical 

 tubercles ; dorsal tentacles laminated, retractile within mar- 

 ginated cavities; oral tentacles leaf-shaped, united into a 

 veil ; branchiae united at the base, non-retractile. Tongue 

 narrow, with 2 large denticulated spines and 6 or 8 rudimentary 

 ones ; no central plate. A spinous buccal collar, with a 

 rudimentary under jaw 



D. repanda, A. & H. 



D. verrucosa, Cuv. 



D. cruenta, Q. & G. 



A. vetulinus, Ehr. 

 D. carinata, Q. & G. 



D. magnifica, Q. & G. 



D. bilamellata, Linn. 



D. depressa, A. kH. 



H. pretextus, Ehr. 



D. pilosa, Mull, 



