124 ] 
RECORDS OF W.A. MUSEUM. 
which there is sometimes to be seen a small pit ; the cirri are 
XX-XXXII, the longest with 37-44 segments, and 35 mm. to 
40 mm. in length ; they are moderately stout and are composed of 
approximately sub-equal segments of which the longest (in the 
proximal portion) are from half again to twice as broad as long, 
and the distal are slightly shorter. 
Remarks. The ten armed species of the genus Amphimetra 
are as yet very imperfectly understood. A considerable number of 
them have been described, mostly based upon single specimens 
which in several cases are small and probably immature. Extensive 
material from any one locality commonly shows great variation 
in one or more of the characters ordinarily used in specific 
differentiation. 
As we know them at present these species appear to fall into 
three groups; (i) species in which the cirri are very stout with all 
of the component segments much broader than long, the distal 
being slightly longer than the proximal (typified hy A . milhevti) •, 
(2) those in which the cirri are comparatively slender with the 
proximal segments never more than twice as broad as long, usually 
about as long as broad, and always longer than the distal, and in 
which the dorsal spines on the cirrus segments are small, short and 
inconspicuous, developed only in the outer portion of the cirri 
(typified by A. discoidea) and (3) those in which the cirri, while in 
general resembling the cirri of the preceding group, possess large, 
long and conspicuous dorsal spines which are developed to well 
within the basal third (typified by A. jacquinoti). 
The specimens under consideration appear undoubtedly to be 
exceptionally large aud well developed examples of A. discoidea; 
typically discoidea has more slender and more tapering cirri in which 
the longer proximal segments are very nearly or quite as long as 
broad, but the distal are shorter, broader than long ; in typical 
inilherti the cirri are much stouter than in these specimens, the 
segments all being approximately of equal length, though the 
outer are a trifle longer proportionately, about four times as broad 
as long. 
