1904.] FROM EAST AFRICA AND ZANZIBAR, 97 



there, looks as if there were five cusps, but the median cusp is in 

 this specimen thinner and more pointed than in the plates. The 

 liver is large and yellowish. Embedded in the front part of it is 

 the stomach, consisting internally of a large, soft, laminated 

 portion, and a ring of about 120 yellowish, fairly stiff, horny 

 plates. They are not all of the same size, the largest being 

 2 ■ millimetres long and 1 high, and the smallest about half as 

 large. 



This species will perhaps prove to be only a variety of 

 M. arhorescens, from which it is distinguished chiefly by its long 

 ribbon-like branchiae, which gbre it a remarkable appearance. The 

 jaws also present some differences. 



Marionia albo-tuberculata, sp. n. 



One specimen from the neighbourhood of Wasin, East Africa. 

 Dredged. 



According to the notes on the living animal the sides were 

 opaque white, with a reticulate pattern of red-brown. At the 

 centre of each mesh was a small white projection. The back, 

 which was dark brown at the sides and greyish in the centre, bore 

 a similar arrangement of reticulations and projecting spots. The 

 sheaths of the rhinophores were tall, and the wavy edges were 

 turned over outwards. The branchiee were much subdivided, and 

 very large when fully extended. The main stems were of a light 

 greenish grey, and the finer branches of a dark yellowish brown. 

 The velum was plate-like, with five processes on each side, three 

 of which were branched. 



The alcoholic specimen is 45 millimetres long, 15 high, and 

 13 broad. It does not taper to a point behind. The colour is 

 dirty yellow with profuse white markings. The stems of the 

 branchiae are spotted and striped with white. There are nine 

 pairs of branchiae of which the fourth is the largest, but the left- 

 hand plume of this pair is much larger than the other. The 

 middle and left-hand side of the velum are injured. There 

 remain on the right-hand side, starting from the inside, (a) a bifid 

 process, with three branches on each bifurcation, (6) a simply 

 quadrifid process, (c) a simply bifid process, (d) a quite simple 

 process, (e) a tentacle grooved below. Taking into consideration 

 the notes on the living animal, it appears that there was a similar 

 arrangement on the left side and that the middle of the velum was 

 smooth. There is a small oval papilla below the fourth branchia, 

 close to the dorsal margin. The genital papilla is lower down 

 between the second and third branchiae. 



The jaws are yellow, horny, and large, being 9 millimetres long 

 and 4 wide. They bear a single row of strong denticles, 10 of 

 which are very much lai^ger than the rest. Under five of the 

 largest are indications of a second I'ow. The radula is yellow, and 

 consists of forty rows with a maximum formula of 95 -H 1.1.1 + 95. 

 The central tooth is fairly broad and bears three cusps, of which 

 that in the middle is pointed and those at the sides blunt. The 

 Proc. Zool. See — 1904, Vol. II. No. VII. 7 



