424 ^Ir. W. K. Fislier on neio 



and tlie arms are the first mar- 

 giual plates (figs. 5 and 6) ; 

 proximal adambulaeral plates 

 not higher than long ; gonads '2 

 or -4 to each ray. Genotype, 

 Brisinr/a panaynensis, Ludwig . Astro/irus, Fisher. 

 e^. Abactinal skeleton of genital region 

 of rav composed of a uniform 

 armour of thin, spiniferou.*, more 

 or less overlapping plates, but not , 



of independent arches or costfe. 

 y\ Primary plates of disk much 

 larger than the others, •which 

 are small ; gonads 2 to each 

 ray ; an interradial plate, ver- 

 tical in position, is intei'polated 

 between the proximal ends of 

 the first adambulaeral plates, 

 and touches the mouth-plates, 

 but does not encroach upon the 

 actinal surface as in Colpaster. 

 Genotype, BeJgicella racovitz- 



ana, Ludwig Belgicella, Ludwig. 



/^. Primary plates of disk not con- 

 spicuous and not distinguish- 

 able from the other abactinal 

 plates of disk. 

 g^. An azygous inten'adial plate, 

 shield-shaped and conspic- 

 uous superficially on the 

 actinal surface, separates the 

 first pair of free adambulaeral 

 plates ; gonads unknown. 

 Genotype, Colpaster scuti- 



peridus, iSladen Colpaster, Sladen. 



g"^. First pair of adambulaeral 

 plates not separated by an 

 azygous plate, but united as 

 in Brisinga, and above them 

 is a pair of conspicuous, 

 united, fi^rst marginal plates — 

 four in all in each interradial 

 angle ; gonads numerous, in 

 a series along either side of 

 the ray. Genotype, FregiUa 



spuiosa, Perrier' Freyella, Perrier. 



(P. Iso syzyo:y, or non-muscular sym- 

 physis, betweenthe first and second 

 adambulaeral plates nor between 

 the upper part of the second and 

 third ambulacral plates, but a nor- 

 mal muscular symphysis not diffe- 

 rent from the others ; no marginal 

 plates directly above the first pair 

 of adambulaeral plates ; the latter 

 are not united except sometimes by 

 the proximal ends; touching the 



