4 Clarh — A Revision of Tlialassometridse and Himeronietridse. 



(P more than 10 arms; opposing spine, when present, snl)-central 

 to sub-teniiinal, more or less directed forward. 

 e^ cirrus joints all much broader than long, sub-equal; cirrus 

 spines paired; Pj greatly enlarged and stifl'(7) Cenometra. 

 «- distal cirrus joints shorter than (or longer than) the proximal, 

 the latter at least as long as broad ; dorsal cirrus sjiines 

 single, or absent. 

 /^ cirri stout basally, tapering gradually to a point distally; 

 terminal claw nearly straight (8) Craspedometra. 



P cirri not tapering distally. 



g^ one or more of the proximal pinnules very stiff, straight, 

 sharp-pointed, and spine-like, though not especially 

 enlarged ; lateral processes on the i Br and further tlivi- 

 sion series (9) Stephanometra. 



g^ proximal pinnules always taper distally to a slender and 

 delicate tip ; no lateral processes on the i Br and furtlier 

 division series. 

 h^ II Br 4 (a -t- 4); Pd smaller than Pj ; F., the longest; 

 arm division very irregular (10) Heterometra. 



7i^ II Br and subsequent division series 2 ; arm division reg- 

 ular (11) Dichroinrtra. 



SUPPLEMENTARY KEY TO GENERA WITH TEN ARMED REPRESENTATIVES. 



a^ no pinnule on the fourth (epizygal) brachial (i. e., Pa al)sent). 



b^ cirri long, with inore than 85 joints; all the pinnules long and stiff, 

 none of the proximal pinnules greatly longer than the others 



(2) Coloboinetra. 



b^ cirri short, with less than 30 joints ; distal pinnules soft and delicate ; 



one or two of the proximal pinnules much longer and stiffer than 



the others (3) Cyllometra. 



a^ a pinnule on the fourth (epizygal) brachial (i. e., Pa present). 



6' middle and distal brachials extremely short an<l (Hscoidal; i Br and 

 lower l)rachials swollen (4) Amphimctra. 



6^ middle and distal Ijrachials wedge-shajjed or triangular, not particu- 

 larly short (()) Oliyoinetra. 



SUPPLEMENTARY KEY TO GENERA W ITU II ISK 4 (.■! + 4). 



a' Pu larger and longer than Pi, which, in turn, is larger and longer tlian 



P^ (5) Himeromctra. 



a^ Pd smaller and weaker than P,, which, again, is smaller and weak(>r 



than p2. 



6' cirri uniform, not tapering distally; distal cirrus joints not so long as 



broad; opposing si)ine present. 



c^ middle and distal brachials exceedingly si loit, discoidal; i J>r and 



lower brachials swollen (4) Amphinietra. 



c^ middle and distal brachials not especially short, more or less 



obliquely wedge-shaped ; i Br and lower brachials not swollen 



(10) Heterometra. 



W cirri tapering distally ; distal cirrus joints twice as long as broad ; no 



opposing spine (8) Craspedometra. 



