OF THE SIBOGA-EXPEDITION. 131 
almost in a straight line; the second brachial is much 
larger, irregularly quadrate. The arms are all broken, but 
the size of the animal is about that of an average A. 
mediterranea. 
P, is 13.5 mm. to 16 mm. long with from eighteen 
to twenty-one segments, moderately slender, more so than 
in the other species of the genus, tapering evenly from 
the base to the delicate tip; the first segment is not quite 
so long as broad, the second decreases slightly in diameter 
distally and is about as long as the proximal diameter, 
the third is between two and one half and three times as 
lonz as broad, and the following are somewhat over three 
times as long as broad, becoming slightly longer distally ; 
the segments have straight sides and no production of the 
distal edges, but the outer have very slightly swollen 
articulations; Pa is similar, but not quite so long; P, 
is 7 mm. long with fourteen or fifteen segments, much 
more slender than P,, though the proportions of the 
component segments is similar; P, is 5 mm. long with 
eleven segments, slender and weak; the segments beyond 
the second being much elongated; P, is 5 mm. long 
with ten segments, slender and weak, similar to the pre- 
ceding but more slender beyond the third segment; P, 
is 6 mm. long with thirteen segments, slightly stouter 
than P, with slightly shorter segments; P, is 7.5 mm. 
long with fourteen segments, similar to P, but with 
slightly shorter segments which have more expanded ends. 
Type locality. — »Siboga” Station N°. 139. 
Compsometra iris, sp. nov. 
This new species is nearest to C. serrata, but the pin- 
nulars have only moderately developed spinous overlapping 
edges instead of having these excessively developed as in 
C. serrata, the brachials have much less prominent spinous 
overlapping distal edges, and the cirri are stouter and 
more curved with shorter distal segments. 
Notes from the Leyden Museum, Vol. XXXIV. 
