426 



PERCY SLADEN TRUST EXPEDITION. 



(A. & H.) is perhaps a colour-variety of this species in which the dark brown and black 

 are replaced by red, but provisionally it is better to keep it separate. 



After an examination of the type specimens I have no doubt that Fl. eurychlamys, B., 

 and Fl. coriacea, Abraham, are the same. I have compared with them specimens 

 from East Africa which I identify with the D. scabra of Quoy and Gaimard. Though 

 the description given by these authors deals with the external features only, it contains 

 so many details that I have no doubt of the identification. Cuvier's D. scabra is 

 unrecognizable from his description, but Quoy and Gaimard may have had access to his 

 specimens. At any rate, their interpretation of D. scabra would seem to be authori- 

 tative. D. solea, Cuvier, is also unrecognizable, and it is not even certain that it is a 

 Flatydoris, for Cuvier seems to contrast its texture with D. scaber. 



Bergh admits (Siboga Exp. Opisth. p. 136) that his Fl. arrogans and Fl. cruenta 

 (Q. & G.) are synonyms. It is possible that Fl. striata, Fl flammulata, and 

 PI. sanguinea are all varieties of the same species. The constant feature in the colour- 

 pattern is that the dorsal surface bears numerous fine lines which seem to be engraved 

 on it. Three variations of this scheme occur : (a) in Fl. striata, there is no red, only 

 a yellow isli ground bearing darker lines ; (b) in Fl. cruenta and Fl. flammulata the 

 pattern is similar but splashed with red ; (c) in Fl. sanguinea the red spreads all over 

 the dorsal surface, but a black reticulate pattern is seen below it. But at present the 

 diflferences reported to exist in the armature of the genitalia make it difficult to unite 

 the species. With regard to these differences, ampler data are required before we can 

 know whether a particular form of spine or scale is of specific value. The real charac- 

 teristic of the genus is that the efferent ducts of the genitalia are lined with an 

 unusually thick cuticle, which is thi-own up into ridges and prominences. These latter 

 generally form (in the male branch) distinct discs bearing spines, but it is not impossible 

 that in some individuals these discs and spines may be imperfectly developed and 

 appear merely as lumps. But only a few specimens of each form have been dissected. 



The genus as at present known may be tabulated as follows : — 



12. 



I 



I 

 \ 3. 



I 4. 



I 5. 



6. 



7. 



!»■ 



PI. scabra (Cuv. and Q. & G.). 



= PI. coriacea (Abraham). 



= PL eurychlamys, B. 



PI. vicina, B., is probably a 

 variety. 

 PI. cruenta (Q. & G.). 



= PL arrogans, B. 

 PL striata (Kelaart). 

 PI. sanguinea, B. 

 PL flammulata, B. 

 PLformosa (A. & H.). 

 PL ellioti (A. & H.). 

 PL inframaculata (Abraham). 

 PL speciosa (Abraham) . 



10. Pl.?variegata,B. 



11. PL ? tabulata (Abraham) . 



12. PLpulchra,'E\iot. 



13. PL herdmani, Farran. 



All the above are from the Indo- Pacific. 



14. Pl.punctateUa,B. W. Coast of S. America. 



15. PL argo, L. Atlantic and perhaps also 



Indo-Pacific. 



16. PL philippii, Med. 



17. PL ? punctata, d'Orb. Canary Islands. 



18. PL angustipes (Morch). W. Indies. 



