1904.] MARINE FAUXA OF ZANZIBAR. 309 



shows a close relationship in other respects besides the compound 

 setfB considered above. The general form of the body, insertion 

 and length of the tentacles, late commencement of the gills, form 

 of the ventral cirri, and details of the setae other than those men- 

 tioned above, are all points in which this species differs from both 

 E. tibiana and U. Jioridana and approaches E. tuhifex. At the same 

 time the difference between the two species in all these charactei's 

 is perfectly distinct. 



The smaller specimens ;\ve not at once recognisable as belonging 

 to the same species, striking and interesting differences occuiiing 

 between them and the full-grown examples. 



Two of the fragments consist of a head and fifty segments each, 

 measuring 35 mm. in length by 4 mm. in breadth, the third of a. 

 head and 35 segments measuring 13 mm. in length and 2'5 mm. 

 in breadth. 



Fi-agments of two tubes were dredged with the above-named 

 specimens, and these differ from those of adults in being soft 

 find translucent. The proj)ortions of the body, head and its 

 appendages are as above, though the sides of the body are not 

 so vertical because the secretory pads are much less developed. 

 These are in proportion about one-third the size to which they 

 attain in the full-grown specimen, remaining conical in shape 

 and being without the free lappet ventrally. Their maximum 

 ■development is shown in the figure of the 30th foot (text-fig. 55). 



Text-fie-. 55. 



30 -'F- 



Tliirtietli foot of a young specimen of ^. tuhifex, to show maximum 

 development of the secretory pad. X 18. 



The jaws of the larger of these fragments are in shape and pi-o- 

 portion like those described above, but the numbers of the teeth 

 are somewhat smaller, as shown by their formula 4 — 4: 8 + 2 — 8. 

 In the smallest of all a great difference in the appearance of the 

 whole is broiight about by a further lessening of the number of 

 teeth and by the delicate translucent brown material of the plates. 

 Fig. 7, PI. XXL, i-epresents this a,ppai'atus, and a comparison of 

 this with text-fig. 53, A (page 306), shows that in other respects 

 the jaws of young and full-grown examples are alike. 



