MUSEUM OF COMPARATIVE ZOOLOGY. 231 



Ophiomitra exigua sp. nov. 



Plate I. Figs. 4-6. 



Special Marks. — Six short, blunt, not thorny arm-spines. Upper siuface 

 of disk nearly covered by large naked radial shields, and sparsely set with, 

 thick, club-headed, thorny stumps. 



Description of an IndividtLal (off Havana). — Diameter of disk 2.5 mm. 

 Length of arm about 18 mm. Width of arm close to disk, without spines, 

 7 mm. 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, tajjering, 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 Ltm. 



Ophiacantlm chelys "Wyv. TnoM., Voyage of the "Challenger," The Atlantic, Vol. 



II. p. 64, Figs. 16, 17. 1877. 

 Ophiomitra chclijs, Bull. Mus. Comp. Zoiil. Vol. V. No. 7, p. 153, PI. IX. Figs. 



239-241. 1878. 



Station 2, 800 -f 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 wth the disk instead of sunken. See 

 Bull. Mus. Comp. Zool. he. cit. 



Ophiomitra cervicornis Ltm. 



Ophiomitra cervicornis, 111. Catal. Mus. Comp. Zool. No. VIII. Pt. II. p. 14, PI. II. 

 Figs. 19, 20. 



Sigsbee, off Havana, 175 fathoms, 4 specimens. Sigsbee. off Havana, 242 

 fathoms, 1 specimen. 



Ophiomitra sertata Ltm. 

 Ophiomitra sertata, BuH. Coini>. Zool. I. No. 10, p. 326. 1869. 

 Sigsbee, off Havana, 175 fathoms, 1 specimen. 



