182 
for most of its length, and the diameter of the animal increases 
rapidly to the distal end of the IBr,, but more gradually from 
then on, so that the opposite sides of the animal åre more nearly 
parallel; this gives these species a peculiarly robust appearance, 
in contrast to the more slender A. Zdepida. While the basal portion 
of A. longicirra increases uniformly in thickness, the increase is 
much more rapid than in 4. Zepida; it is a considerably stouter 
and more robust species, with a larger centro-dorsal, and the I Br 
are sharply tubercular, a chåracter quite absent in the latter. 
Being confronted with an entirely new species of AÅsterometra 
in general appearance quite unlike the species with which I was 
previously acquainted, I was not at first sure that I was not 
dealing with a new species of Ptilometra; externally the two genera 
are much alike, except for the more abrupt termination of the 
arms in Asterometra, and the more slender and tapering cirri of 
Ptilometra; but the muscular fossæ on the distal faces of the 
radials in Ptilometra, like those of Calometra, are extremely reduced 
and very narrowly linear so that they are scarcely visible in a 
lateral view; in Asterometra, on the other hand, though small, 
they are of the ordinary rounded character, resembling most closely 
those of the Thalassometridæ. Upon laying bare one of the radials 
of the new species, I found the characteristic muscular fossæ of 
Asterometra, which removes all possible doubt in regard to its 
systematic position. 
Genus Tropiometra A. H. Clark. 
Tropiometra 1907. A. H. Clark, Smiths. Misc. Coll. (Quart. Issue), 
Vol. 50, p. 349. 
Tropiometra carinata (Lamarck). 
Comatula tone == Lamarck, Hist. Nat. des Animaux sans verte- 
bres, Vol. 2, 
Alecto rasen ye MS 
le us Litken, M. S. 
Tropiometra carimata 1907. A. H. Clark, Smiths. Misc. Coll. (Quart. 
Issue), Vol. 50, p. 349. 
SE len 1905. Bell, Marine Investigations in South Africa, Vol. 
8, p.1 
