Cunha; tra to South Africa éuid the ( rozel 

 [slands, and eastward i<> the Ivermadec, Galapagos, 

 Hawaiian and western Alcutian [slands, and southern 

 Japan; littoral, and down to 2926 Metres) Thalassometrinae 



i* 1 Subfamily Ptilometrinae A. II. Clark. 

 Ki\ to the Genera of the Subfamily Ptilometrinae. 



Centrodorsal laree and broad. thick discoidal or columnal. the numerous cirri 

 oselj crowded and irregularly distributed, though tending to arrange them- 

 selves in fifteen columns; the radial areas of the centrodorsal are never 

 differentiated southwestern, southern, and southeastern Australia) Ptilometra 

 a Centrodorsal a short, more or less pentagonal, column, with a conical apex ; 

 the comparativelj few cirri are arranged in ten definite columns, two to each 

 radial area; the radial areas are separated from each other by more or less 

 de-, ridges 



b 1 10 — 13 arms; the pinnules in the proximal third of the arm are much 

 shorter than those in the distal half, and are composed of segments 

 which, except occasionally at the extreme tip, do not have overlapping 

 and spinous distal ends; the longer proximal cirrus segments have 

 approximately straight ventral and dorsal borders (as viewed laterally) 

 which are usually parallel, though they may diverge very slightly distally ; 

 there is no central constriction, or production of the distal edge (Lesser 



Sunda I slands to southwestern Ja [jan) Asterometra 



1>- 20 — 30 arms; the pinnules in the proximal third of the arm are as 

 long as, or even longer than. those in the distal half, and are composed 

 of segments mam or most of which are constricted centrally with 

 produced and spinous distal ends; the longer proximal cirrus segments 

 are usually mort: or less constricted centrally with prominent distal ends 

 the ventral border of which usually more or less overlaps the base of 

 the succeeding segment, and may be produced into a long ventral spine 

 ilf of Martaban to northern Celebes and the Philip- 

 pinelslands) Pterometra 



Asterometra A. II. ('huk. 



Key 1 Species of the Genus Asterometra. 



Elements of the IBr series and hrst two brachials without prominent median 

 Is or tubercles 



b 1 cemrodorsal small and conical Formosa) lepida 



centrodorsal large, columnar, with a conical ap 



