330 PERCY SLADEX TEUST EXPEDITION. 



connected witJi the dispai-ity of size, I have ranked them as a yariety of the Mediterranean 

 species. 



Both the specimens measured less than half the length of an example of P. chrysocoma 

 from Nnples in the University Museum of Zoology here, while P. inclica from Ceylon 

 (Willey) and tbe Pliilippines (Grube) varied from 14-26 millimetres. On the other hand, 

 P. indica possesses 43-46 segments, in contrast to the 35 of P. chrysocoma and 34 in this. 

 In shape the Zanzib;ir worms resembled P. clirysocomn, being broadest in the middle, 

 not tapering from the head as in P. indica. 



The head is distinctly marked off and almost spherical in shape. Claparede's figure 

 does not indicate it properly. The tentacles are exactly as described for the Naples 

 form, save for the absence of papillse from tbe basal joint ; they exactly resemble the 

 corresponding structures in the genus Palmyra. The palps appear quite smooth when 

 examined under a good dissecting-lens ; a high power, liowever, shows a number of tiny 

 appendages (fig. 27). Willey's specimens possessed markedly ciliate pal[)s, but Claparcde 

 figured those of P. chrysocoma as smooth. 



The elytra number fifteen pairs, and are thin and membranous. The first pair are 

 distinguished in no way from those that follow, while in P. chrysocoma they are said to 

 be rudimentary and possess a border with fringing processes (CUiparede). In Naples 

 specimens they are much thicker and somewhat smaller than the succeeding elytra, but 

 their processes are not so prominent as those figured by Claparede, so that this appears 

 to be a variable character. 



As the structure of the parapodium in this genus has not been fully described, a 

 figure is given here (fig. 26) to show the relation of the parts. The notopodium bears 

 three kinds of setal structures : — 



(1) The thread-like setse which form the dorsal felt. Two kinds are described : 

 (a) thicker smooth threads, and (b) much finer threads with tiie " articulated " appearance 

 figured in the French monograph. Both occur in our specimens. 



(2) The greatly enlarged palea-like spines. In general shape they resemble those 

 drawn by Claparede [t. c. pi. 1. fig. 3 b), but the tip is blunt rather than acute. There 

 are, moreover, considerably more serrations (fig. 36). 



(3) Below are numerous very fine setiE with a smooth shaft and a long gradually 

 tapering tip, which is covei-ed with minute ciliate processes, giving a hairy ajipearance 

 to tlie whole (fig. 36). In length these setse exceed those of the neuropodium, though 

 they fall short of the spines above. There is no mention of this variety of seta in the 

 above-quoted descriptions, but I have examined specimens from Naples which possess 

 a tuft of tliese sctte on the notopodium, though not so large proportionately as in these 

 East-African forms. 



The dorsal felt is much thicker and more entangled than in those from Naples. It 

 contains two or three specimens of a curious Isopod with elongated limbs, but it is 

 uncertain whether this is really commensal or just accidentally entiuigled. The curious 

 appearance wliich is due to the accumulation of detrital particles round the paleaj and 

 dorsal felt is shared also by P. indica (in which Grube speaks of the paleae as " immer 

 mit vielem Schmutz gedeckt "). 



