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Show 182 PROF. F. JEFFREY BELL ON THE [Mar. 1, proof, if more were needed, of the acumen of the distinguished naturalist who proposed them. For the Zygophiurans assistance in classification will be gained from Ljungman's well-known work l, and the families may be disposed thus :- C I. Arm-incisures on the disk. 1- Ophiodermatidce. a. N o dental papillae <( 2. Ophiolepedidce. | II. Arms inserted on ventral surface of disk. (^ 3. Amphiuridce. f I. Oral papillae present. ft. Dental papillae. \ T T xf• Ophiocomidce. r r II. N o oral papillae. [ 5. Ophiothricidce. 5. THE RELATION OF OPHIOTERESIS TO FOSSIL FORMS. Zittel places in the suborder Euryaleae ( = Cladophiuree) the genera Onychaster and Eucladia, of which he says (Handb. d. Pal. p. 444) that they are " die einzigen fossilen Formen, welche mit einiger Sicherheit zu den Euryaliden gestellt werden konnen." But Eucladia, as described by Dr. Woodward (Geol. Mag. 1869, p. 241), has the madreporite on the abactinal surface, whereas all Ophiuroids have that plate actinal in position. As I purpose to confine myself for the present to the Ophiuroids, I need not discuss what is the exact systematic position of Eucladia, beyond urging that it should be recognized as a form which cannot be placed in the group Ophiuroidea, as now recognized. Onychaster has the granular investment which is now found onlv in Astrophiuroids,but the articular surface of the arm-ossicles appears to be rather on the Streptospondyline than the Astrophiuroid (hourglass- shaped) type. Tceniaster (Billings, Geol. Surv. Canada, Canadian Organic Remains, dec. iii. p. 80) and Protaster (Forbes, M e m . Geol. Surv. U. K., dec. i. pi. iv.) are examples of a group of which the most salient known fact is the absence of ventral arm-plates. I have no information as to the character of the faces of their arm-ossicles; but, as the arms of both are flexible, I have no doubt that their proper place is with the Streptophiurae. 6. THE RADIAL SHIELDS OF OPHIOMAZA OBSCURA. In his description of this species Herr Ljungman (op. cit. p. 333) says, " in dorso scutis radialibus maximis gibboso-carinatis." So far as I can discover, this species has not been seen by any subsequent student of the group, and no figure of this very interesting species has been published. Its discovery by Mr. Bassett-Smith off the N.W. coast of Australia (Bassett-Smith Bank, 9 fathoms) extends its geographical range, as the type was taken off Singapore. The figure which is now given 1 Op. cit. |