296 MR. CYRIL CROSSLAND ON THE [Feb. 16, 



broad, two ai'e rather less elongated, and one is somewhat less 

 broad. The acicular setse project more or less and so are subject 

 to wear in use, as a result of which the hooks and gu.ard are not 

 often found perfect (when they correspond exactly with Gravier's 

 figure) but usually more or less damaged. The larger and posterior 

 hook being the most exposed is seen to wear away the faster, so 

 that in many cases where attrition has gone furthest, the remnants 

 of both hooks are of nearly the same size, the whole then 

 resembling Gravier's figure of this seta in E. mutahilis. 



A consideration of the range of variability set forth above 

 enables us to estimate the grounds for regarding Gravier's 

 two species, mutahilis and perri6?'i, as synonymous with afra Peters 

 {collaris Grube). 



The former {I. c. p. 245) differs from the examples regarded as 

 typical in its unifoim pigmentation, the position of the eyes, and 

 the complexity of the gills. 



The eyes are placed on the swollen bases of the median pair of 

 tentacles, a condition found frequently in these specimens of 

 E. afra (PI. XX. fig. 5). (From Gravier's text and an exami- 

 nation of the present examples, it is evident that this appearance 

 is exaggerated in the fig. I. c. pi. xiii. fig. 71.) 



The gills are unusually complex for a specimen of this size, but 

 agree in size and distribution with the above. The setse figured 

 for E. miotahilis difi'er slightly from those given for E. collaris 

 (cf. figs, on pp. 247 & 253 I. c), but, as explained above, such 

 variations are common in this as in other species of the Eunicidee. 

 The jaw-apparatus calls for no remark, its formula being 4 — 4 : 

 4_}-3_5. In his description of the buccal segment of both 

 E. mutahilis and E.jierrieri, but not in that of E. collaris (= afra), 

 Gravier mentions a projecting lobe laterally, which is present also 

 in all the specimens here dealt with and seems rather characteristic 

 of the species. For its appeai'ance and proportions see the side 

 view of the head figured, PI. XX. fig. 2. 



As regards the supposed new species E. peri-ieri, the arrangement 

 of the pigment in a mosaic so frequently met with is sometimes 

 artificial and due to the wrinkling of the skin, and a sirailar color- 

 ation of the tentacles (the distal part being uniformly pigmented, 

 not banded) is common, though not the rule. 



The groove behind the middle tentacle, described here but not 

 mentioned in the cases of E. mutahilis or E. collaris, and figured by 

 Gravier on pi. xii. fig. 58, is more or less distinct in all the present 

 specimens. Often its sides are raised into distinct lips, which form 

 the white streak described above in the case of the Prison Island 

 specimen (see PI. XX. fig. 5). The more ventral position of the 

 first few feet has already been remarked upon. The gills in large 

 specimens with their twenty filaments are much more complex 

 than any hitherto met with in East Afiica or the Maldives. The 

 differences between the descriptions and figures {I. c. p. 234) of 

 seta3 given for E. collaris and E. 2'>errieri are very trifling, even 

 more so than in the case of E. mutabilis. 



