128 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxxiii. 



KEY TO THE SPECIES DESCRIBED. 



A. Ten-armed species, with the disk and ambulacra plated, but the rays not wall- 



sided; the pinnules stiff and rod-like [ Accela group]. 



a. First radials produced anteriorly, separating the second radials; second radials 



and axillaries rounded and widely separated (29) Antedon thetis. 



aa. The radials have flange-like lateral processes, which are in apposition later- 

 ally (4) A. separata. 



B. Bidistichate species, with the disk and ambulacra plated, but the rays not wall- 



sided ; the pinnules stiff and rod-like [Multicolor group]. 



a. First radials anchylosed, forming a radial cup with interradial processes reach- 

 ing to the disk and widely separating the rounded second radials; 15 cirri 



of 35 joints (l)-^i- multicolor. 



aa. First radials not anchylosed; interradial processes very narrow, lower part of 

 second radials meeting above them; larger part of the second radials and 

 the axillaries widely separated laterally: 20-25 cirri of 45 joints. 



(2) A. versicolor, 

 aaa,. First radials appear as small interradial triangles with no distal process; sec- 

 ond radials in api:)Osition for entire lateral edge, but axillaries widely 



separated (3) A. propinqua. 



aaaa. The radials have flange-like lateral processes, which are in apposition later- 

 ally. 

 h. Lower brachials (and distichals when present) rounded, and widely sepa- 

 rated from those on adjacent rays (4) ^4. separata. 



bb. The first distichals have flange-like processes, and are in apposition laterally, 

 c. Cirri short, with 30 short joints; the second or third (or both) pairs of pin- 

 nules much elongated; first radials only just visible. 



(5) A. flavopnrpurca. 



cc. Cirri long and slender, with 40 elongated joints; the proximal pinnules 



not elongated; first radials large and prominent (6) A. callista. 



C. Ten-armed species, in which the radials and lower brachials have flattened sides. 



[Basicurva group.] 

 a. Pinnule aml^ulacra plated. 



b. The later cirrus joints have dorsal spines. 



c. First pinnule smaller than the second; cirri three-fourths length of arms, 



with 80 joints; dorsal surface of railials smooth (7) A. anthus.O' 



cc. First pinnule nearly or quite as long as the second; cirri longer than the 



arms, with about 110 joints (8) A. macropoda.a 



ccc. First pinnule longer than the second. 

 d. Over 60 cirrus joints. 

 e. First pinnule much flattened exteriorly; cirri very slender, with about 

 70 joints; radials and brachials strongly carinate; arms compressed, 



with prominent overlapping spines (9) A. hana. 



dd. 30 to 50 cirrus joints. 



e. First pinnule flattened on outer side; much larger and stouter than 

 second. 

 /. Cirri in 15 vertical rows; radials and lower brachials thickly set with 



short spines (10) A. villosa.a 



ff. Cirri in five well-separated double vertical rows; radials and lower 

 brachials bordered with stout spines (30) A. hawaiieyisis. f> 



« Also a bidistichate species; see p. 129. 

 f> Also a tridistichate species. 



