558 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
Key to the Ophiuroids of the Woods Hole region. 
Arms simple, unbranched. 
Arm spines short, small, and more or less apgressed to the arm. 
Arms nearly terete; disk covered with a fine granulation Ophiuka brevispina 
Arms flattened; disk covered with scales Ophioglypha robusta 
Arm spines prominent, at a marked angle with the arm. 
Upper-arm plates surrounded by a series of small plates; arm spines 5 to 6 Ophiophous aculeata 
Upper-arm plates not surrounded by small plates; arm spines 3 Amphipholis squamata 
Arms dichotomously branched l Gop.gonocephalus agassizii 
1. Ophiur a Brevispina Sat'. (PI. 5, figs. 28-30; pi. 7, figs. 37,38.) 
Ophiura brevispina Say, 1825. 
Ophioderma olivaceum Ayres, 1852. 
Ophioderma serpens Lutken, 1856. 
Oplii nr a brevispina Lyman, 1860 and 1882. 
Ophiura olivacea Lyman, 1865; Verrill, 1873. 
Description. — Arms normally 5, occasionally 4, rarely 6, of moderate length, nearly terete, but 
flattened on the oral side. Diameter of disk, 10 to 15 mm. Length of arm, 40 to 60 mm.; breadth of 
arm at base, 2J to 3 mm. Arm spines 7 to 8, shorter than the arm joints, approximately equal, or the 
lowest shortest, closely appressed to the arm. Disk more or less perfectly pentagonal, covered with 
granules of nearly uniform size, about 100 to 180 to a square millimeter, completely concealing the 
radial shields. At the base of each arm the granulation extends out on each side, so that the first 3 
upper-arm plates form a narrow ridge running in toward the center of the disk. On each side of the 
third plate is a group of about 10 little scales. Upper-arm plates broadly in contact with each other; 
at the base of the arm they are nearly oblong, twice as wide as long, but as the tip is approached they 
become more rounded on the sides, the outer edge becoming curved, the inner markedly narrowed. 
Under-arm plates broadly in contact, nearly square with rounded corners, usually somewhat longer 
than wide. First under-arm plate much wider than long, with rounded sides; second much longer. 
Tentacle scales 2, of which the inner is nearly half the length of the under-arm plate, while the outer 
is about half as long and covers the base of the lowest spine. Oral shields oval, plainly longer than 
wide. Adoral plates small, lying entirely at sides of oral shields, roughly triangular, with rounded 
corners. All of the oral surface granulated as above, except the oral shields and adoral plates. Oral 
papillae about 7 on each side of each jaw, of which the one next to the under-arm plate is small, often 
wanting, while the next one is the widest and largest of all. Teeth 5, blunt, the lowest the smallest. 
No tooth papillae. In each interbrachial space there are 4 genital openings. Color very variable, but 
never very bright; some shade of green or brown is the most frequent; the disk is generally mottled 
or spotted, and the arms frequently banded with alternate rings of light and dark shades. More or 
less uniform olive green is a frequent color, uniformly brown specimens being less frequent; nearly 
black specimens are occasionally found. 
Range. — North Falmouth, Mass., to Bahia, Brazil, low water to 122 fathoms. 
Remarks. — This very widely distributed brittle star reaches its northern limit in Buzzards Bay. 
It is abundant in about 1 fathom of water, on a bottom covered with eel grass, in North Falmouth 
Harbor, and has been taken in similar situations in Marion, New Bedford, and Dartmouth, Mass., on 
the other side of the bay. It also occurs at Sag Harbor, Long Island. The habits, movements, and 
development have been so well described by Grave (1900) that it is unnecessary to discuss them here. 
Verrill (’99) considers the northern form of this species as separable from the form occurring from 
Florida southward, and would regard it as a variety olivacea. 
2. Ophioglypha robusta (Ayres). (PI. 6, figs. 31, 32; pi. 7, 39, 40.) 
Ophiolepis robusta Ayres, 1851. 
Ophiura fasciculata Forbes, 1852. 
Ophiura squamosa Lutken, 1854. 
Ophioglypha robusta Lyman, 1865. 
Ophioglypha tenorii Ljungman, 1866. 
Description. — Arms 5, finely tapering. Diameter of disk, 7 to 10 mm. Length of arm, 24 to 35 
mm.; breadth of arm at base 1 to 1.5 mm. Arm spines 3, rounded and acute, the upper one largest, 
nearly 1 mm. long; at tip of arm- the lowest spine is flattened and bears 1 or 2 small hooks. Disk 
rounded or slightly pentagonal, covered with small, irregular scales, 4 or more to the square millimeter; 
in young specimens, the plates at center of disk show more or less definite arrangement. Radial shields 
inconspicuous, about as broad as long, barely touching without. The disk is notched in each radius 
