Arm spines erect, not adpressed to arm.

Oral shields entirely covered by granules: arm-plates usually concentrically striated: 6 or more hyaline arm-spines.

Ventral arm-plates longer than wide, and contiguous: 1 tentacle-scale: teeth widened at free end. . . . Ophiurodon Matsumoto, 1915.

*Ophioconis grandisquama Koehler, 1904. Indonesia. 250 fms.

Ventral arm-plates wider than long, contiguous only on basal joints: 1 or 2 tentacle-scales: teeth pointed at free end. . . . Ophiuroconis Matsumoto, 1915.

*monolepis Matsumoto, 1915. Japan. 100 fms.

Oral shields naked.

Arm-plates concentrically striated; one large tentacle-scale. . . . Toporkovia Djakonov, 1954.

*fragilis Djakonov, 1954. N.W. Pacific, 200 fms.

Arm-plates not concentrically striated: arm-spines opaque: 2 tentacle-scales.

Disc bearing scattered spinules among the granules: no accessory oral shield. . . . Ophiurochaeta Matsumoto, 1915.

*Ophiochaeta mixta Lyman, 1878. Caribbean. 100 fms.

See note under Ophiacantha, p. 18.

Disc without spinules: an accessory oral shield. . . . Ophiarachna Mueller & Troschel, 1842.

*Ophiura incrassata Lmk., 1816. Indonesia. Littoral.

Arm spines short, adpressed to arm, or partly imbedded in granulation.

Single tentacle-scale.

Oral shields entirely covered by granules.

Arm-spines hyaline. . . . Ophioconis Luetken, 1869. (s. restr. Matsumoto, 1917).

*Pectinura forbesi Heller, 1862. Mediterranean. Littoral.

Arm-spines 6 to 9, opaque. . . . Cryptopelta H. L. Clark, 1909.

(Ophiodyscrita H. L. Clark, 1938, resembles Cryptopelta, but has the arm-plates concealed by granules: it is probably the juvenile form.)

*Ophiopeza aster Lyman, 1879. S. Africa. 150 fms.

Oral shields naked: 2–4 arm-spines.

Ventral arm-plates entire: radial shields partly exposed. . . . Bathypectinura H. L. Clark, 1909.

*Pectinura lacertosa Lyman, 1883. Caribbean. 1,500 fms.

Ventral arm-plate of each joint subdivided into a narrow proximal plate and a broad distal plate: radial shields not exposed.

Dorsal arm-plates entire: distal end of genital cleft not extending to the dorsal margin of disc. . . . Ophiopaepale Ljungman, 1872.

*goesiana Ljungman, 1871. Caribbean. 100 fms.

Dorsal arm-plates fragmented to form a mosaic: distal end of genital cleft extending to dorsal margin of disc, so as to be visible from above. . . . Schizoderma Nielsen, 1932.

*diplax Nielsen. 1932. Gulf of Panama. Littoral.

Two tentacle-scales.

Genital clefts divided into two subsidiary apertures, so that 4 genital apertures lie in each interradius.

Proximal cleft lies on ventral side, close to oval shield, but distal cleft lies on dorsal side of disc, beside radial shield. . . . Diopederma H. L. Clark, 1913.

*Ophiura daniana Verrill, 1867. San Salvador. Littoral.

All genital clefts lie on ventral side of disc.

Arms densely clothed in granules, with only the arm-spines and 2 tentacle-scales emergent. . . . Ophiocryptus H. L. Clark, 1915b.

*maculosus H. L. Clark, 1915b. California. Littoral.

Arms not granulated, arm-plates visible.

Proximal cleft long and narrow, the distal one circular and smaller. . . . Ophioncus Ives, 1889.

*granulosus Ives, 1889. Loc. and depth not stated, presumably Eastern N. America.

Distal cleft larger than proximal one. . . . Ophioderma Mueller & Troschel, 1840.

The "Stella laevis" of Rondelet (1554) is probably Ophioderma.

*Asterias longicauda Retzius, 1805. N. Atlantic. Littoral.

Genital clefts entire, 2 genital apertures in each interradius.

Spines present on disc. . . . Ophiochaeta Lütken, 1869.

*hirsuta Lütken, 1869. Fiji. Littoral.

Only granules on disc.

Radial shields concealed by disc granulation.

Marginal scales at periphery of disc enlarged and conspicuous: disc not notched at insertions of the arms. . . . Ophiopezella Ljungman, 1872.

*Ophiarachna spinosa Ljungman, 1867. Indonesia. Littoral.

Disc without enlarged marginal scales.

Dorsal side of arms densely granulated, concealing the arm-plates. . . . Ophiocormus H. L. Clark. 1915.

Syn.: Ophiostegastus Murakami, 1944.

Ophiocormus was stated by H. L. Clark to have only one tentacle scale, and was therefore referred to Ophioconis by Matsumoto (1917). This is an error, however. Dr. Elizabeth Deichmann, who kindly examined the holotype at Harvard on my behalf, informs me that there are 2 tentacle-scales.

*notabilis H. L. Clark, 1915. New Zealand. Littoral.

Arms without granulation, disc more or less notched at the arm-insertions.

One supplementary dorsal arm-plate on either side of dorsal arm-plate. Ophioclastus Murakami, 1943

*hataii Caroline Island.

No dorsal supplementary arm-plate.

Oral shield entire, without a supplementary plate at the distal margin. Ophiopeza Peters, 1851.

Syn.: Ophiopsammus Lütken, 1869.

*fallax Peters, 1851. Mozambique.

Oral shield with a distal supplementary plate.

Having an inner row of six or seven small aciculate arm-spines, more or less covered by an outer row of seven or eight larger spines: two tentacle-scales on the first six to eight segments, the inner one the longer. . . . Distichophis Ely, 1942.

*clarki Ely, 1942. Hawaii. Littoral.

Having a single row of arm-spines. . . . Pectinura Forbes, 1843.

*vestita Forbes, 1843. Mediterranean. Littoral.

Radial shields not covered by granules.

Interradial spaces between adjacent radial shields much wider than adradial spaces between pairs of shields. . . . Ophiarachnella Ljungman, 1872.

*Ophiarachna gorgonia Mueller & Troschel, 1842. Indian O. Littoral.

Interradial and adradial spaces between adjacent radial shields about equal: the radial shields large, forming a conspicuous ring around the disc. . . . Ophiochasma Grube, 1868.

Syn.: Ophiopinax Bell, 1884.

*Ophiarachna stellata Ljungman, 1867. Indonesia. Littoral.