1906.] OF SOUTHERN INDIA AND CEYLON. 655 



Bergh says (Siboga, I. c.) that only Th. maculigera, Th. carinata, 

 Th. tristis, and Th. hilaris ca,n be included in the genus with 

 certainty, though it is noticeable that he originally (Semper's 

 Reisen, xvii. 1890, p. 913) marked Th. carinata with a query. 

 Th. dubia and Th. pallida seem to conform fairly well to the 

 generic diagnosis, though in the descriptions of the dorsal surface 

 it is very difficult to linow exactly what is meant by Zotten, 

 Knotchen, and similar terms. 



Th. ? clandestina B. is smooth and the external teeth are not 

 denticulate. Th. ladislavii was described by von Ihering (" ISTudib. 

 der brazil. Kiiste," in Mai. Jahrb. xiii. 1866, p. 234) as Etidoris, 

 but Bergh in his ' System ' regarded this genus as a synonym of 

 Thordisa. The validity of the genus Etidoris may be doubted, 

 but, as von Ihering remarks, the animal described by him comes 

 near to Archidoris. It is tubercvilate ; the tentacles are thick and 

 grooved, and the rhachis of the radula bears thickenings. It differs 

 from Archidoris only in having the outermost teeth denticulate. 

 Doris millegrana was described briefly by Alder and Hancock 

 (Monogr. pt. vii., Appendix, p. i). Von Ihering {I. c. p. 238) 

 created for it the genus Aporodoris, regarded by Bergh in his 

 ' System' (p. 1098) as a synonym of Thordisa, but in the Opistho- 

 branchia of the ' Siboga' Expedition (p. 94) recognised again as a 

 separate genvxs and provided with a second species, Aporodoris ? 

 rubra. The genus remains very doubtful, but, so far as the 

 descriptions permit one to judge, seems allied to Archidoris. 

 Alder and Hancock do not hint at any affinity between their Doris 

 millegrana and their Doris (Thordisa) villosa. Thordisa caudata 

 Farran has not a villous back, and is perhaps referable to Trippa. 

 See below vmder Trippa luteola. Th. crosslandi is discussed below. 



The remarkable Doris lanuginosa* of Kelaart, which is " green 

 and covered with short downy hair," is perhaps a Thordisa or 

 Diaulula. 



Thordisa villosa (A. & H.). 



(A. & H. 1. c. p. 119. Eliot, Proc. Zool. Soc. 1903, ii. p. 367-8. 



Cf. Thordisa maculigera Bergh, in Semper's Reisen, Heftxii. 



p. 540. Id., Danish Exped. to Siam : Opisthobranchia, 



p. 182.) 



Two specimens, labelled Doris villosa, are preserved in fair 



condition. They differ somewhat in appearance. One is larger 



and more leathery than the other, and its dorsal tubercles are 



hard and warty. The smaller specimen is softer and the back 



villous rather than warty, the dorsal tubercles bearing soft 



filaments. It still resembles Alder and Hancock's plate \l. c. 



pi. xxxiii. fig. 1), and I also have but little hesitation in referring 



it to the same species as the specimens from Zanzibar described 



by me {I. c.) as Thordisa villosa. 



Further, it seems to me almost certain that the species, as 



* No drawing of tliis species was fonnd. 



Proc. Zool. Soc— 1906. No. XLIV. 44 



