246 
BULLETIN OP THE UNITED STATES FISH COMMISSION. 
All of the 6 specimens of Ophiopsila before me agree in having 2 tentacle scales, of which the 
outer is from one-fourth to one-lialf the length of the inner. The latter is as long or longer than the 
arm joint and is generally spatula-shaped, but in 2 specimens is narrower and more pointed. The 
shape of the upper-arm plates varies greatly, as already mentioned, and the under-arm plates also vary 
in shape and distinctness. The oral shields also vary from long diamond-shape, longer than broad, to 
broad shield-shape, much broader than long. There is some slight variation in the number and size 
of the oral papillae and tooth papillae, but in general the specimens agree fairly well. 
23. Ophiopsila riisei Lutken. 
This species occurs throughout the West Indies and south to Brazil in shallow water among 
rocks or coral. There are 2 tentacle scales, of which the inner is very long and spatula-shaped. One 
very good specimen of this form from station 6079, and another, much smaller and broken, from 6080. 
The latter has the disk gray, with black spots, and the upper-arm plates, instead of being almost square, 
are twice as long as wide and the outer end rounded. 
24. Ophiactis krebsii Lutken. 
This is a common little ophiuran from Bermuda and South Carolina to Rio Janeiro, among corals 
in shallow water. There are generally 6 arms, 5 to 6 times the diameter of the disk. Oral papillae 
usually 2 on a side. There are 6 small ophiurans in the collection, which I have referred to this 
species. Of these, 4 from Mayaguez reefs and 1 from Playa de Ponce have 6 rays each and the usual 
green and white coloring; but 1 from station 6080 has only 5 rays, and the colors are pale yellow and 
brown. In all other respects it agrees with the others. All are small, with disks from l\ to 4 mm. in 
diameter. 
25. Ophiactis longibrachia, nov. sp. (PI. 14, figs. 1 to 5.) 
Rays 5, long and slender. Disk 13 mm. in diameter; arms 100 mm. long; . • . r= 7\ d. Arms 2 
mm. wide at base. Disk almost circular, hiding the bases of the arms, covered with small but thickish 
scales, which are evident only when dry. Over the whole surface of the disk are scattered numerous 
very small, almost smooth, blunt spines, and these also cover the interbrachial spaces below. Radial 
shields long and rather narrow, separated at the inner ends, but touching at the outer extremities, 
smooth and naked. Upper-arm plates granular, wide and short, 3 or 4 times as wide as long, rounded 
at the sides. Arm-spines 7 (figs. 3 to 5) except on the first few joints the next to the uppermost 
generally longest, the others regularly shorter to the lowest, which is a little longer than the single 
large short and blunt tentacle scale. Under-arm plates almost square, with lateral edges markedly 
raised. Oral shields small, much broader than long, with a blunt angle inward. Adoral plates large, 
somewhat longer than wide, outer end the wider, meeting each other within. Oral papillae 1 or 2, at 
the distal end of mouth slit, above the oral tentacle, separated, somewhat bluntly conical. Genital 
slits 2 in each interbrachial space. Color above, disk almost olack, with outer ends of radial shields and 
the little spines whitish (under a lens), arms brown, tinged with purple; beneath, disk black, mouth 
parts and under side of arms at bast pale yellowish; outwardly the under side of arms gradually 
becomes darker, until it is the same shade as above. 
The only known specimen of this species was taken at station 6096, off Vieques Island, in 6 fathoms 
of water, on a coral bottom. It comes near to 0. dispar of Verrill, which it resembles in some important 
particulars. It differs from that species in its much larger size, greater length of arms, markedly 
different color, and size and shape of the adoral plates, while there are slight differences in the arm- 
spines and oral papilla* and in the scaling of the disk. 
The West Indian species of Ophiactis need careful revision from a large series of specimens, and 
when that is done this, as well as dispar , may prove to be the adult form of some one of the previously 
known species. The name given has been selected because of the unusually long arms. 
26. Ophiactis loricata Lyman. 
This uncommon species was originally described from Florida, where it was taken in water from 
10 to 110 fathoms deep. The oral papillae are 2 on each side. There is a single small Ophiactis from 
Mayaguez, which is clearly not krebsii and is probably this species. It is very small, with no disk 
spines, 6 arms with 4 arm-spines, and 2 mouth papillae. The color is purple and white variegated. 
