1903.] MARINE FAUNA OF ZANZIBAR. 139 



Marphysa mossambica Peters. (Plate XY, figs. 7-10.) 



Maiyhysanovce-hollandice Grube, Annulata Semperiana, p. 165. 



M. mossamhica Gravier, Nouv. Arch. Mus. de Paris, 1900; 

 also Kinberg & Peters. 



The most complete description of this species is that recently 

 given by Gravier, following on, and adding figures to, that of 

 Grvibe. 



The species occurs abundantly in Chuaka Bay, Zanzibar, living 

 in deep burrows where the sand is of some consistence, i. e. well 

 above low-water mark. In obtaining specimens for bait, the 

 natives dig pits two or three feet deep, scooping away the sand 

 from the circumference until a suflicient number of the worms has 

 been met with. My own specimens were obtained in this way, 

 through the natives, except two younger ones, which were 

 fovmd under the bark of a tree which lay half buried in the 

 sand. 



The worm is of fair size, a foot or two long, by nearly half an 

 inch wide when alive. Its colour is a dark blood-red, with a green 

 iridescence anteriorly, the red being obscured, however, only 

 by the black gut posteriorly. No pigmentation occurs except 

 certain small marks on the prostomium described below. 



The shape of the anterior end of the body (PI. XV. fig. 7) is very 

 characteristic of this as of several other species. The head and 

 first few body-segments are proportionately long and i-ound in 

 section, forming a cylinder, but at about the fifth they become much 

 broader and especially shorter and flatter. The broadest segment 

 is usually about the twelfth, after which a slight decrease in 

 breadth occurs, the rest of the worm having parallel sides and being 

 composed of very shoi't and flat segments. From about half an inch 

 bef oi'e the anus the segments rapidly narrow, so that the hind end 

 is triangular (see Pl.'XY. figs. 7 & 9). The upwardly directed 

 thick-lipped anus and its cirri are as figured by Gravier, but his 

 figures of both head and anus suggest that the woi-m increases and 

 decreases in breadth but slightly, and quite gradually. 



I find no reduced eyes on the pi'ostomium. The pigment-marks 

 at the bases of the tentacles and under the anterior border of the 

 peristomial segment are shown in fig. 8, PI. XY., which shows 

 also the rings round the lower ends of the tentacles mentioned by 

 Gravier. The tentacles are always distinctly more slender, and 

 appear to arise nearer together than those shown by Gravier's figure. 



The dental apparatus is soft and brown in the two young speci- 

 mens, very hard and black in the adults, a veiy little white 

 matter occurring on the lower or mandibular plates. The upper- 

 most tooth of the right great dental plate is always smaller and 

 duller than the corresponding one on the left, and those of the 

 right cvirved lateral plate are all longer than those of the left. 



Except near the extremities of the body, the feet present the 

 peciiliarity of being provided with no more than the stumps of 

 their setae. This, which would appear a mere regrettal^le accident 



