1904.] 



MARINE FAUNA OP ZANZIBAR. 



293 



furtlier vary considerably in the numbers of the teeth they bear, 

 as evidenced by the following formulas * : — 



(1) 4-5. 



(2) 6-7. 



(3) 4-5. 



(4) 4-5. 



(5) 4-4. 



7 + 4-8. 



7 + 6-9. 



6 + 4-7. 



8 + 5-9. 



7 + 6-11. 



The widely different formulae (2) and (3) are both from the set 

 of specimens collected at Chuaka. 



Jaws of IS. afra, from a Inrge speciiiieii from Chuaka. In such c\'evy part is hlack 

 or dark brown, except a narrow border to the lower jaws. The end-plates of 

 the lower jaws are partly calcareous. Contrast the same in a young specimen, 

 as shown in PI. XX. fig. 4, and compare the latter witli PI. XX. fig. 7, which 

 represents these parts in li. coccinea. 



The lower jaws bear oval calcareous end-plates whose cutting- 

 edges are almost always entire (PL XX. fig. 4 and its explanation). 

 The general shape of the A^arious pieces, as shown by text-fig. 44, 

 is constant. 



The feet are well developed thi-oughout the body, and all bear 

 gills except the first fifteen to twenty and those of the last few 

 reduced segments. These attain their maximum development 

 only in the anterior third of the branchiferous region, where, in the 

 Maldivan specimens, they are composed of the usual numbers of 



* See Grube, Jor. cit. p. 19. 



