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 % and the families may be dis- 

 posed thus : — 



r I. Arm-incisures on the disk. 



I 1. Ophiodei^matidce. 



a. No dental papillae <( 2. Ophiolepedidce. 



I II. Arms inserted on ventral surface of disk. 



1^ 3. Amphiuridce. 



' I. Oral papillge present. 



4. Ophiocomidce. 

 II. No oral papillse. 



5. Ophiothricidee. 



/3. Dental papillee. 



5. The Relation of Ophioteresis to Fossil Forms. 



Zittel places in the suborder Euryalese ( = Cladophiuree) the genera 

 Omjchaster and Eucladia, of which he says (Handb. d. Pal. 

 p. 444) that they are " die einzigen fossUen 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 jilate 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 only 

 in Astrophiuroids,but the articular surface of the arm-ossicles appears 

 to be rather on the Streptospondyline than the Astrophiuroid (hour- 

 glass-shaped) type. 



TcEniaster (Billings, Geol. Surv. Canada, Canadian Organic Re- 

 mains, dec. iii. p. 80) and Protaster (Forbes, Mem. 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 Streptophiurse. 



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 subse- 

 quent 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 oflF Singapore. The figure which is now given 



^ Op. cit. 



