3658 PERCY SLADEN TRUST EXPEDITION. 
degree their ranges overlap, they are at present separated as much by their geographical 
habitats as by their structural differences. 
They agree, however, among themselves in the following characters :— 
Their flattened rectangular form (twice as wide as high). 
Oval head with 4 eye-spots, short appendages, the median tentacle shorter than the 
lateral, scarcely as high as the caruncle. 
The caruncle ending in the middle of the third segment or beginning of fourth. 
Three or four buccal segments forming the sides of the mouth. 
Jointed dorsal and ventral cirri not so long as the bundles of sete. 
Gills consisting of a large number of branches. 
The dorsal setze containing characteristically a subfurcate type (Gravier, text-figure 262), 
the outer limb of which may or may not be serrate, and the straight serrate 
gradually tapering seta which is apparently common to all species (Gravier, text- 
figure 266). 
The ventral setze belonging to a much stouter furcate type (Pl. 46. fig. 20), the rami 
not slender but stout and curved: the outer ramus may or may not be serrated. 
To my mind a species with the above characters is a perfectly natural one. There 
are, however, fairly wide limits of variation. 
The only valid cause for separation of these “ species” is found in the slight variations 
of the sete. 
E alcyonia, as described by Gravier * (from a single specimen only, however), and 
E. complanata never possess furcate setee with serrations on the outer limb of the fork. 
In £. pacifica the setee of the dorsal and ventral bundles are typically serrate, but 
McIntosh mentions the fact that in the specimens of LZ. pacifica from Ceylon belonging 
to the British Museum, one does not show distinct serrations. This, then, appears to be 
a variable character, and it is questionable how far it should be used to define a separate 
species. 
~ In the present collection the majority of specimens examined (including all the larger 
examples) showed no serration of sete. 
In a homogeneous group of specimens like those from Funafuti it is noticeable 
that in the smaller individuals the posterior border of the mouth is formed by the fourth 
body-segment and not by the fifth as in the larger. Thus the number of buccal 
segments varies between four and five, and it is not safe to give a definite number of 
buccal segments as a specific character as Kinberg has done in his diagnoses of species f. 
The trilobed character of the smaller forms at least is not easy to make out. Here 
again the. period of growth influences the structure of organs, and the larger and 
older specimens alone show the fully developed caruncle with crenated lateral lobes. 
The succession of setee has not been sufficiently studied in these forms and a few facts 
with regard to this may well be added. In all specimens examined, the three types of 
* Gravier, Nouv. Arch. de Mus. d’Hist. Nat. sér. 4, t. iii, 1901, pp. 248-254, 
+ Kinberg, Ofversigt af Vetenskaps-Akad. Forhand, xiv. 1857. 2. kamehameha and E. pacifica have four 
buceal segments, E. corallina three. Savigny’s original specimens of L. alcyonia from the Gulf of Suez had three 
buccal segments, but Gravier describes the species as possessing four. 
