NUDIBRANCH I AT A. 555 



Gen. Platydoris B.' 



Flat, oval animals of a fair size and peculiar hard, leathery texture. The back is finely 

 granulated and rough to the touch : the mantle margin ample : the foot grooved in front 

 and the upper lamina deeply notched. The branchial opening is generally stellate : the 

 branchiae are tripinnate and usually five, six or seven in number. There is no labial 

 armature or rhachidian tooth. The radula consists of numerous hamate laterals, the outermost 

 of which are sometimes finely serrulate. The reproductive organs have an armature of hard 

 scales, bearing hooks. 



The Platydorids are recorded from the Indian Ocean, E. Africa, the Pacific (including 

 the W. coast of America), the Mediterranean, Great Britain {PI. planata), the West Indies, 

 and the Canaries. They may therefore be considered as cosmopolitan. They are frequent 

 on coral reefs under stones at low tide. They are exceedingly lethargic and are often found 

 wedged into the crevices of stones, the mantle having gro^vn into the shape of the hollow 

 in a way which suggests that the animal has not moved for a considerable period. Several 

 of the species show the same phenomenon of self-mutilation as Discodoris. 



16. PL eurychlamys B. 



One specimen from the Kolumadulu Atoll, Maldives, 33 f. The animal as preserved is 

 7 cm. long and 4 cm. broad. The back, which is as usual flat and leathery, is blackish- 

 brown, with white spots, which are particularly numerous near the margin. The underside 

 dirty white, with black spots on the foot. The rim of the branchial pocket white; the 

 branchiae six, whitish with black rhachis. The numerous teeth are of the ordinary hamate 

 type ; the outermost are very irregular in shape but not serrulate. 



From Bergh's descriptions of various specimens the colour appears to be very variable. 



17. PI. scabra Q. and G. 



One small specimen from Minikoi 3"5 cm. long by 1'7 cm. broad. Not dissected. This 

 species, which I have frequently seen alive in the South Seas, is hard and leathery and 

 grows to be three or four inches long. The mantle is wavy and indented. The labial 

 tentacles small, white and tapering. The rhinophore sheaths somewhat projecting. The colour 

 of the back is white ■ivith irregular blotches of brown formed by aggregations of minute 

 spots. The under surface yellowish-white. The branchial aperture has six lobes and presents 

 a star-like appearance. The branchiae are six, yellowish, very voluminous and delicate". 



18. Platydoris sp. 



Two specimens from the Maldives, Hedufuri, Mahlos Atoll. The largest is 2'2 cm. long 

 by '9 cm. broad, the form being somewhat elongate. The back is finely granulated, bluish- 

 white, with traces of yellowish-brown mottlings in the centre. Round the mantle margin 



1 Bergh in S. R. Hefte xii., xvi., xvii., and Supp. Heft i., foot which are mottled like the back. The branchiae are 



and Savimlung, Plate, Opisthobranchiata. light yellow with grey axes : the rhinophores, buccal mass 



- As there seems to be no description of this species except and viscera all bright, light yellow. The foot small and 



Quoy and Gaimard's brief notes, I add the following par- narrow, grooved in front and notched, but not deeply: the 



ticulars taken from specimens examined in East Africa. The upper lamina thick. No trace of labial armature. Badula 



living animal is as much as 10 cm. long, very stiff, yellowish- about 4S x 60 . . 60. Teeth simply hamate : innermost 



white, with irregular violet mottlings of varying intensity, smaller, two or three outermost irregular. Male branch of 



formed mostly by minute rings of the same colour with reproductive organs with the characteristic hook-bearing 



yellowish centres or by spots. The under side is a clear scales apparently set in four rows : female branch with 



yellowish-white, with no markings except at the sides of the strong folds. 



71—2 



