494 THE VOYAGE OF H.M.S. CHALLENGER. 
Chorological Synopsis of the Species. 
Ocean, | Range in Fathoms. | Nature of the Sea-bottom. 
| Hymenaster anomalus  . : Atlantic. 1425 Pteropod ooze. 
Hymenaster cexlatus . : i Southern. 1800 | Globigerina ooze. 
Hymenaster carnosus : : Pacific. 1500 Globigerina ooze. 
Hymenaster coccinatus  . : Southern. 1375 | Globigerina ooze. 
Hymenaster crucifer ; om Southern. | 1800 Globigerina ooze. 
Hymenaster echinulatus . | Pacific. 2335 Red clay. 
Hymenaster formosus : | Southern. 1800 Globigerina ooze. 
Hymenaster geometricus . 6 Pacific. 2335 Red clay. 
Hymenaster gibory? . c F Atlantic. 2214 os 
Hymenaster glaucus . : | Pacific. 565 Green mud. 
Hymenaster granijerus  . | Southern. 1375 | Globigerina ooze. 
Hymenaster infernalis . il Pacific. 2900 Red clay. 
Hymenaster latebrosus . 0 Southern. 1950 Diatom ooze. 
Hymenaster membranaceus : Atlantic. 1125 Blue mud. 
Hymenaster modestus : : Atlantic. 1098 to 1451 = 
Hymenaster nobilis . : : Southern. 1800 Globigerina ooze. 
Hymenaster pellucidus . ; Atlantic. 70 to 1539 | Clay (various kinds). 
Hymenaster pergamentaceus . Atlantic. 2650 Blue mud. 
Hymenaster porosissimus . Se Pacific. 1375 Globigerina ooze. 
Hymenaster precoquis . i Southern. 1375 to 1600 { ata tna 
Hymenaster pullatus : : Pacific. 1070 Blue mud. 
Hymenaster rex : ; ail| Atlantic. 601 to 1093 068 
Hymenaster sacculatus . : Southern. 1800 Globigerina ooze. 
Hymenaster vicarius : ° Pacific. 1375 Globigerina ooze. 
Synopsis of the Species included in the Genus Hymenaster. 
A, Adambulacral armature consisting of one spinelet. 
a. Paxille-crowns forming raised areas of membrane. Spiracula small, 
numerous, equidistantly spaced . : 5 5 5 ; : . nobilis, 
b. Paxille-crowns not forming raised areas. 
a. Spiracula single, large, uniformly spaced. . . jformosus. 
6. Spiracula in groups of six to ten, small, irregularly disuribated . pergamentaceus. 
B. Adambulacral armature consisting of two spinelets. 
a. Muscular fibrous bands of supradorsal membrane coherently reticulated. 
a. Paxille-crowns forming definite areas. Spinelets not prominent . sacculatus. 
6. Paxille-crowns not forming definite areas. Spinelets very prominent. 
a, Spinelets forming a raised keel over each radius. Spiracula 
large, single, distributed . : : 5 . . echinulatus. 
fB. Spinelets not forming a raised keel. Spiracula microscopic, 
in groups of ten or more . 5 2 : .  carnosus. 
b. Muscular fibrous bands of supradorsal membrane simply intoverossitig! 
a. Radial areas elevated in relief above the interradial tissue. Paxille 
with three spinelets . , c : . glaucus. 
6. Radial areas not elevated above the caeeacial Saeee Paxille 
with more than three spinelets. 
