147 



decrease in height and resolve themselves into a sharp carinate 

 process crowned vvith spinules; P,, though longer and stouter 

 than the following, is slender and evenly tapering, composed of 

 segments which beyond the second are much longer than broad, 

 more or less constricted centrally, with produced and spinous distal 



edges (Yucatan to Grenada, West In dies) Stylometra 



c'- less than 15 (10 — 13, usually 10) arms; division series usually 2, 

 sometimes 4 (3 -f- 4) ; Pj very stout, much stouter than the succeeding 

 pinnules, though with a delicate tip (Morocco and Madeira 

 southward to Ascension and the Crozet Islands; east 

 Africa to the Kermadec, Galapagos, Hawaiian and 

 western Aleutian Islands, and southern Japan). . . Thalassometra 

 b 3 ossicles of the division series and of the arm bases smooth, without 

 spines on the dorsal surface, though they may have irregular processes 

 on their lateral borders ; P v though larger and stouter than those suc- 

 ceeding, is not especially enlarged 

 c 1 not more than 15 arms 



d 1 cirri with more than 50 segments, very long and very slender ; arms 

 slender, very narrow, strongly compressed laterally ; a prominent 

 narrow median keel on the ossicles of the division series, which 

 is continued the entire length of the arms; 10 — 12 arms; division 

 series 2 ; proximal cirrus segments with a distinct keel in the mid- 

 dorsal line, and usually with a small spine in the middle of the 

 distal dorsal edge (Oueensland and Ti mor to the Philip- 



pine Islands; southern Japan) Daidalometra 



d 2 cirri with less than 35 segments 



e 1 cirri with 30 — 34 segments, of moderate length and moderately 

 slender ; ossicles of the division series broad, very slightly 

 convex dorsally but with a prominent sharp median carinate 

 process, everywhere in close lateral apposition ; lateral portion 

 of the distal borders of the IBrj, IIB^ and the first brachial 

 produced, forming rounded thin anterior processes which im- 

 bricate over the bases of the succeeding ossicles ; brachials 

 with a very faint and obscure median carination ; 13 — 15 arms; 



division series 2 (southwestern Japan) Lissometra 



e 2 cirri with at most 27 (usually between 20 and 25) segments, short 

 and stout; division series and arm bases well rounded dorsally, 

 appearing narrow and only slightly flattened against their 

 neighbours; 10 — 20 arms; division series 2 (Kei Islands 

 to southern Japan and the Hawaiian Islands) . Parametra 

 c 2 more than 1 5 (usually 20) arms 



