MUSEUM OF COMPARATIVE ZOOLOGY. 231 
Ophiomitra exigua sp. nov. 
Plate I. Figs. 4-6. 
Special Marks, —Six short, blunt, not thorny arm-spines. Upper surface 
of disk nearly covered by large naked radial shields, and sparsely set with 
thick, club-headed, thorny stumps. 
Description of an Individual (off Havana).— Diameter of disk 2.5 mm, 
Length of arm about 18 mm. Width of arm close to disk, without spines, 
7mm. Three short, pointed, tooth-like mouth-papilla on each side of an 
angle, with one larger and diamond-shaped at the apex. Mouth-shields very 
small, triangular, with an angle inward and outer side rounded. Side mouth- 
shields very large, wide, and swollen, longer than broad, meeting within. 
Under arm-plates small, pentagonal, with an obtuse angle within, and wide 
outer edge much rounded, and with re-entering curves on the lateral sides. 
Side arm-plates large, flaring without, meeting broadly below, but only touch- 
ing above. Upper arm-plates small, somewhat swollen, fan-shaped, with the 
angle inward. Disk constricted in the interbrachial spaces and irregularly 
puffed ; almost the entire upper surface is occupied by the large triangular, 
swollen, naked radial shields, which are joined their entire length. In the 
centre is a small patch of irregular scales with five radiating, single, interbrachial 
rows, and others along the margin. Scattered irregularly are very stout, club- 
shaped stumps with a crown of strong thorns. Six short, blunt, tapering, not 
thorny arm-spines, evenly spaced along the spine ridge ; the upper one is the 
longest. One flat, rounded tentacle-scale. Color in alcohol, blue-gray. 
Sigsbee, off Havana, 240 fathoms, 1 specimen. 
Ophiomitra chelys Lym. 
Ophiacantha chelys Wyv. Tuom., Voyage of the “Challenger,” The Atlantic, Vol. 
II. p. 64, Figs. 16, 17. ۰ 
Ophiomitra chelys, Bull. Mus. Comp. Zoól. Vol. V. No. 7, p. 153, Pl. IX. Figs. 
239—241. 1878. 
Station 2, 800 + fathoms, 2 specimens, Station 15, 785 fathoms, 1 specimen 
(young, var. Station 41, 860 fathoms, 2 specimens. Sigsbee, off Havana, 480 
fathoms, 2 specimens (young, var.). 
Most of the specimens presented variations from the type, especially in 
having the radial shields nearly level with the disk instead of sunken. See 
Bull. Mus. Comp. Zoól. loc. cit. 
Ophiomitra cervicornis Lym. 
Ophiomitra cervicornis, 111. Catal. Mus. Comp. Zoól. No. VIII. Pt. II. p. 14, Pl. IT. 
Figs. 19, 20. 
Sigsbee, off Havana, 175 fathoms, 4 specimens. Sigsbee, off Havana, 242 
fathoms, 1 specimen. 
Ophiomitra sertata Lym. 
Ophiomitra sertata, Bull. Comp. Zool. I. No. 10, p. 326. 1869. 
Sigsbee, off Havana, 175 fathoms, 1 specimen. 
