144 ON THE MARINE FAUNA OF ZANZIBAR. [June 16, 



All authors agree as to the characteristic form of the eyes. As 

 noticed by Grube and seen in the present collection, they vary in 

 breadth from narrow crescents to kidney- or bean- shape, yet never 

 becoming merely oval. 



The lower or mandibular jaw-plates are most characteristic in 

 constitution and form, being usually calcareous with special plates 

 of brown or black homy material. Marenzeller's figure is the 

 only adequate representation of a very beautiful structure. The 

 number of teeth on the left great dental plate varies fi-om three 

 to five, though usually it bears, as does always the right, four 

 teeth. The curved laterals are exceptionally variable, as shown 

 by the formulae 3 + 5 — 5; 5-f 1-5 ; 3-fl — 5; 3 + 3—3; 

 4+5-3. 



All authors agree in making the dorsal and ventral cirri much 

 longer than those figured by Gravier. In all the specimens I 

 have examined, their tips extend as far as do the lips of the seta- 

 sac, or in anterior feet a little further. 



The articulated pieces of the compound setse are not always 

 the shape of an equilateral triangle, being usually somewhat longer. 

 Their shafts are bent and broadened distally, and the striation and 

 the toothing at the point opposite the articulation (mentioned by 

 Gi'avier, but best seen in Marenzeller's figure), like the bordering 

 of the capillary setag, are not always distinct. 



The acicular sette always bear two distinct hooks, when not 

 damaged by wear, as sometimes happens, but only in a few cases 

 does their covering or winging remain. 



EXPLANATION OF THE PLATES. 



Plate XIV. 



Fig. 1. Diopafra neapoUtana (p. 132). Ventral view of the head after removal of 

 the jaw-apparatus. 



oes., 03Sopliagus ; b.tv., body- wall ; a, lip o£ jaw-sac ; b, lip of oesophagus 

 with its tubercles. 



2. OnupMs liolohrancliiata (p. 135). Head and anterior end, showing the 



characteristic pigmentation. 



3. Marphysa macintoslii, sp. nov. (p. 137). Head and anterior end. 



4. 25th foot of the same. 



5. Compound seta3 from 25th foot. Comb-setse from the 100th foot. The whole 



free length of these is represented. 



6. 160th foot of the same. 



Plate XV. 



Fig. 7. Anterior end of Marphi/sa mossamhica (p. 139), showing the proportions of 

 the body in spirit-specimens. 



8. Ditto. The front edge of the peristomium is cut away to show the pigment- 



marks on the tentacles and prostomium. 



9. Hind end, anus and its cirri. 



10. Group of comb-setse from one of the posterior feet, showing the extent of 



their projection from the seta-sac. 



11. Marphysa simplex, sp. nov. (p. 140). The ringing of the tentacles is rather 



too strongly emphasised in this figure. 



12. Group of comb-setfe from the 60th foot. 



13. Marphysa fiircellata, sp. nov. (p. 141). Head and anterior end. 



14. Tip of seta-sac of 120th foot, shewing the short strong combs characteristic 



of the species. 



