ORDER II 



OPHIUROIDEA OPHIUREAE 203 



Woodw. Disk granulated. Each of the arms giving off five 

 pairs of secondary branches, which ,\ /, 



increase in size outwards. One 

 niadreporite present. Silurian : 

 England, 



'7>".s/</\ Meek and Worth. 

 (Vntral disk round, small. Arms five, 

 simple, long, and covered with a tuber- 

 culous int e^unient, in which fine scales 

 are embedded. Sub - Carboniferous ; 

 North America. 



? Hcliitiithiixtcr, Roemer. Disk large, 

 granulated. Arms sixteen, long, broad, 

 and covered with a granulated integu- 

 ment. Lower Devonian ; Bundenbach. dorgal coverin of the v ,. Iltril (lisk is r - (MlloV ed ex- 



.' Kiin/tllc, Lam. It is possible that posing the mouth franu-. /., M.iutli tVami- .-ular-i-il, 

 , , j ! i i viewed from above ; c, vertebral ossicle, enlar^ 1 ' 1 '- 



the rough impressions described by 



Quenstedt as Euryale liasica, from the Angulatus Bed of Niirtingen (Lias a), 



also belong here. 



Order 2. OPHIURBAB. Miiller and Troschel. 



Arms invariably simple, incapable of being rolled up towards the mouth, and, as 

 " /'///', cased with four series of integumentary plates. Silurian to Recent. 



Mouth shields are well developed in recent forms, one of them serving as a 

 madreporite ; but they are absent in all fossil species. 



Sub-Order 1. OPHIO-ENCRINASTERIAE. Stiirtz. 



Arms without ventral shields, the lateral elements of the vertebral ossicles dis- 

 junct, and alternately arranged. Mouth shields absent. Disk covered with skin or 

 fine scales, sometimes spinous. Silurian and Devonian. 



To this sub-order belong the following genera : Protaster, Forbes, from the 

 Silurian of England and America. Taeniaster, Billings ; Silurian. Eugaster, 

 Hall ; Devonian. Palaeophiura and BundenbacJiia, Stiirtz ; Lower Devonian. 



Sub-Order 2. PROTOPHIUREAE. Sturtz. 



Arms without dorsal, sometimes without ventral shields. Elements of the verte- 

 bral ossicles placed opposite one another, and more or less anchylosed. Disk without 

 either radial shields, mouth shields, or genital scales. Silurian and Devonian. 



The % sub-order is divided by Sturtz into three groups, comprising the 

 following species : 



(a) Ophiurina Lymani, Sturtz. Lower Devonian ; Bundenbach. 



(b) Protaster Miltoni, Salter. Silurian ; England. Furcaster palaeozoicus 

 and Ophiurina Zitteli, Sturtz. Lower Devonian ; Bundenbach. 



(c) Ophiura primigenia, O.Decheni, and O.Rhenana, Sturtz. Lower Devonian; 

 Bundenbach. 



