REPORT ON THE NUDIBRANCHIATA. 
49 
9. Marionia elegans (Audouin, Savigny). 
Bed Sea. 
10. Marionia cyanobranchiata (Riippell und Leuckart). 
Red Sea. 
11. Marionia occidentalism n. sp. 
Western Atlantic. 
Marionia occidentcilis, n. sp. (PI. XI. figs. 3-15). 
? Tritonia cucullcita, Couth., Gould., Expl. Exped., Moll., 1852, p. 308, pi. xxv. fig. 403, a.-f. 
Habitat. — Western Atlantic. Off Buenos Ayres. 
This species may be identical with Tritonia cucullata of Gould, from the shores of 
Rio Janeiro ; but since this identity, even if it exists, will probably never be certainly 
proved, the name Marionia occidentalis may stand. 
One specimen only was dredged on February 25, 1876, from a depth of 13 fathoms, 
in lat. 35° 2' S., long. 55° 15' W., in the bay of Buenos Ayres. It was well preserved 
in alcohol. 
The total length of the individual was 4 '3 cm., its height 9 mm. and breadth 10 mm. ; 
the breadth of the foot 8 mm. ; the length of the rhinophoria 4 mm., that of the 
branchiae 4 mm. The colour 1 of the animal was of a bright grass green ; the dorsal 
surface is divided by lines into a number of green polygonal areas. The clubs of the 
rhinophoria and the points of the branchial leaves, as well as of the finger-like processes 
of the frontal margin, are whitish or light yellowisli-grey. The sides are of a whitish 
colour, which becomes greenish towards the edge of the mantle ; they are covered all 
over with a number of round or longitudinally oval slightly prominent white spots. 
The circumference of the mouth and the margin of the foot are greenish, but the under 
surface is yellowish. 
The body is somewhat slender; the crescent-shaped frontal veil is small and pro- 
vided with about twenty finger-like processes, wdiich resemble those of other species of 
the genus ; the tentacles are spoon-shaped and not strongly developed ; the club of 
the rhinophoria is provided with about ten bipinnate appendages ; the terminal papilla 
of the rhachis of the hindermost one is very prominent. The branchice are, as in the other 
representatives of this genus, distributed along the margin of the dorsal surface — thirteen 
on each side — the posterior being much smaller than the other. That portion of the 
dorsal margin which lies between the branchiae is concave. Each branchia consists of 
a stem, which is divided into four, three, and two branches, which are again divided into 
two and three branchlets, which terminate in bipinnate twigs. The genital papilla 
1 The living animal is probably green on the upper surface and reddish over the rest of the body. 
(ZOOL. CHALL. EXP. PART XXVI. 1884.) Cc 7 
