1903.] FROM EAST AFRICA AXD ZANZIBAR. 379 



rows, each containing about ten scales. The centi'al nervous 

 system is as usual, with very large and distinct eyes. 



The idea that the specimens are immature is supported by the 

 size, which is small for the genus, and perhaps by the fact that a 

 good many were found together. They are possibly the young of 

 some already described form, and offer certain analogies with 

 PI. vicina, in which, however, only the male reproductive organs 

 appear to be armed with scales (Bergh, Semper's Reisen, Suppl.- 

 Heft i. 1880, p. 63). 



24. Plattdoris papillata, sp. n. 



Nine specimens from Chuaka. 



The living animals were of varying but somewhat sombre 

 coloration, ranging from dark peaty brown to yellowish brown, in 

 all cases blotched with grey or black markings, greatly varying in 

 extent and pattern. The under side of the ample mantle had a 

 whitish border, then a yellowish area covered with minute brown 

 dots, and, lastly, chocolate-bj'own blotches near the foot, sometimes 

 few and separate, sometimes united in a band. The foot was 

 greyish. The gill-pocket closed as in Aster onotus. The dorsal 

 surface was covered with numerous small simple papillae, and also 

 bore some much larger-branched papillae, which may have been 

 as much as half a centimetre long. In the living animal they 

 looked exactly like bits of sand. Their number varied greatly 

 in different specimens : in some they were numerous, in others 

 there were only a few near the mantle-edge. The largest living 

 specimen was 11 cm. long and 7 broad. 



The measurements in alcohol are : length 8*1 cm., breadth 5"1, 

 height 2"8. The mantle-brim very thick and 1"6 wide. The 

 texture of all the specimens, particularly on the mantle-brim, 

 is very distinctly leathery, but not hard or rough. One spe- 

 cimen, with an almost smooth back, presents the appearance of 

 Asteronotus, but is clearly distinguished by the presence of a 

 few branched papillae. Also, in all specimens the back is granu- 

 late, and not smooth as in Asteronotus. The rhinophore-openings 

 are slightly raised and indistinctly crenulate. The branchial 

 pocket can be closed by six lobes which meet over it ; they are 

 not all of the same size, and vary in different specimens. The 

 branchiae are six, tripinnate, and large. The foot is fairly broad 

 and rather amply developed in front, where it has the usual notch 

 and groove. It is, perhaps, as a consequence of this development 

 that the oral tentacles, being pressed between the foot and head, 

 appear flattened in most of the alcoholic specimens, and in some 

 expanded into lobes as in Hexahranchtis. There is no trace of 

 labial armature. The radula is bi-oad, and consists of fi'om 30 to 

 40 rows, containing from 60 to 70 teeth on each side of the 

 rhachis. The teeth are long and simply hamate, the two or three 

 innermost are somewhat degraded ; the two innermost are not 

 parallel to the rest of the row, but are set almost at right angles 

 to it and project into the large bare rhachis (a somewhat similar 

 though less-marked ai'rangement may be seen in Bergh 's figure 



