276 PROCEEDINGS OF THE NATIONAL MUSEUM. VOL, XXXIY. 
eschrichtu or an Antedon bifida were cut off at the costal axillary, 
the costals removed, and the arm (the first brachial) grafted onto 
the radial. This arm arrangement occurs only in 
Thaumatocrinus, Decametrocrinus, and -in “Hudio- 
crinus” atlanticus, japonicus, semperi, tuberculatus, 
and varzans. : 
me. berm Additional proof of the correctness of this interpre- 
rapiaL Faces tation of the arm structure of Decametrocrinus and the 
on axaomm™™* species of “Hudiocrinus” mentioned is found in the 
arrangement of the pinnules; for when a species like 
Decametrocrinus narest or “Hudiocrinus” varians : 
bears a pinnule on the second post-radial joint there 
is always one on the following joint and on all succeed- 
ing, excepting, of course, the hypozygals of syzygial 
pairs. 
Since these five species of “Hudiocrinus ” are really 
in no way related to the type-species (#. endivisus), Me 1 VENTE*t 
VIEW OF RADIAL 
but belong to an entirely different family, they require — racss or Zyco- 
a new generic name, and for them I have proposed the " "MSM 
name of Pentametrocrinus as suggesting their five- 
armed condition, and also their affinity to the closely related Decame- 
trocrinus, with ten arms. 
This involves a redefinition of two families and two genera, as 
follows: 
>) 
Family ZYGOMETRID &. 
A family of Comatulida in which the radial faces are broad and 
low, in lateral apposition (figs. 6, 7), the muscular fosse small, nar- 
row, and crescentic, curving upward and outward from the ridge sur- 
rounding the central canal to the antero-exterior corner of the radial 
faces, and entirely separated from each other by a deep median 
cleft; the costals are united by syzygy, but the first two brachials by 
bifascial articulation; disk plated, but pinnule ambulacra naked; 
five to ninety arms. 
Color variegated and usually brilliant, consisting of red, yellow, 
purple, brown, and white. _ | 
Habitat—Northern Australia northward to Japans littoral, and 
down to 60 fathoms. : 
Included genera—ZLygometra,; Eudiocrinus. 
Genus HUDIOGRINUS (emended.) 
A genus of Zygometridee in which the arms are five in number, the 
second costal not being an axillary (fig. 8); cirri short and stout, 
the joints swollen distally, the opposing spine stout and well de- 
veloped; arm and pinnule joints overlapping. 
