266 PROCEEDINGS OF THE NATIONAL MUSEUM. VOL. XXXIV. 
presence of 4 (3 + 4) costals has only once been detected, but there is 
no reason to believe that it does not more or less commonly occur. 
Hiumerometra stylifer (A. H. Clark). (Fig. 2.) A specimen of 
this species from Kagoshima Bay, Japan, has one arm (arising on the 
inner side of an exterior palmar axillary) which divides at the sixty- 
fourth free brachial; this axillary joint bears a pin- 
nule on the left side; on its distal faces it bears two bra- 
chials, that on the right side bearing a pinnule exter- 
nally, that on the left with none; these are followed 
each by a syzygial pair, which, like the preceding joints, 
are interiorly united; that of the left-hand side bears 
ee nas. a& pinnule on its interior distal corner; the following 
FER; pistaL joints on each arm are normal, and bear pinnules 
eee OSS alternately, as usual, except that the pinnule of the 
second joint beyond the syzygial pair on the left side is only 
visible in ventral view, being forced from its usual position by the 
basal joints of the pinnule of the left syzygial pair, which have 
grown fast to its lateral border. In a dorsal view, it 1s seen that the 
left-hand arm continues the arm anterior to the axillary forward 
almost in a straight line, while the right is at a considerable angle; 
this is especially evident from an examination of the ambulacrum on 
the ventral side of the arm. From the presence of a pinnuie on the 
axillary and on the opposite side one of the following joints, it is 
clear that this is an arm division in no way homologous to the arm 
division resulting from a costal or palmar series; the shape of the 
joints following this axillary also shows them to be distal brachials, 
and the tubercle always present at the junc- 
tion of a first and second brachial in this 
species is lacking. It seems to be best in- 
terpreted as a case of arm splitting, where 
one of the distal brachials has, for some 
‘rause or other, divided (leaving its pinnule 
on the half opposite to the pinnule of the 
preceding joint, now become an axillary) ; 
the next joimts (a syzygial pair) have be- 
come separated stili more (only one of them 
2 5 : Fic. 3.—CHARITOMETRA IMBRI- 
bearing a pinnule), while from here onward OMS SHOVING WARD GUC. 
each of these syzvgial pairs bears a per- COPIDUUNE), IDENISTUILBS ON) RIENE 
SAME SIDE OF THE ARM. 
fectly developed arm. 
Charitometra imbricata (=Antedon granulifera P. H. Carpenter 
1888, not Antedon granulifera Pourtalés 1878=Comatula brevipinna 
Pourtalés 1869=Antedon pourtalesi P. H. Carpenter 1888). (Mig. 
3.) In this specimen the third and fourth brachials are not 
united by syzygy, as usual in an arm springing from a costal axillary, 
and the fourth brachial, instead of bearing a pinnule on the opposite 
