CLARK: THE CRINOID FAMILY ANTEDONIDAE 505 



P 2 resembles Pi, and always differs from, the genital 

 pinnules; P a is frequently, and Pi occasion- 

 ally, absent Perometrinae 



P 2 resembles P 3 and the succeeding pinnules, and 

 often bears a more or less developed gonad; 

 all of the lower pinnules are invariably 

 present Bathymetrinae 



Subfamily ANTEDONINAE A. H. Clark 

 Key to the Genera of the Subfamily Antedoninae 



P 2 of the same length and character as P 3 and the following pinnules, 

 and much shorter than (usually about half as long as) P x . 

 Pinnule segments with unmodified, or at the most with very 

 finely spinous, distal edges; size medium, the arms rarely 

 under 45 mm. in length (Norway to the Gulf of Guinea, 

 including the entire Mediterranean basin and the east Atlantic 

 Islands; Caribbean Sea to Rio de Janeiro, Brazil; 0-445 



meters) Antedon 



Pinnule segments with strongly produced, everted and coarsely 

 spinous distal edges; size small, the arms never over 70 

 mm. and rarely over 45 mm. in length (Southern coasts of 

 Australia northward throughout the East Indian region to 



southern Japan; 0-275 meters) Compsometra 



P 2 not of the same length and character as P 3 and the following pin- 

 nules, and never only half as long as Pi. 

 P 3 of the same length and character as the succeeding pinnules. 

 Centrodorsal flattened hemispherical or discoidal; size me- 

 dium, the arms being between 60 mm. and 120 mm. in 

 length; Pi has 18-40 segments. 

 Pi longer than the cirri, becoming very slender and 

 flagellate distally, composed of about 40 segments 

 (Ceylon to the Society Islands; 0-47 meters) 



Mastigometra 



Pi shorter than the cirri, less slender and more or less 



stiffened, composed of 18-21 segments (Moluccas 



to China, and eastward to the Society Islands; 0-397 



meters) Euantedon 



Centrodorsal conical; size small, the arms being about 30 

 mm. in length; Pi and P 2 have 12-13 segments ('Ha- 

 waiian Islands and northern New Zealand; 108-293 



meters) Argyrometra 



P.i not of the same length and character as the following pinnuh s. 

 P 3 much the longest and stoutest pinnule on the arm. 



The distal ends of the cirrus segments do not overlap 

 the bases of those succeeding; the dorsal edge of 

 the outer four to six cirrus segments is about as 

 long as the proximal border; the brachials have 



