SUMMARY. 



187 



Range of genus from the Trias to existing period. Three British Liassic and Oolitic 

 species (Vol. II, pp. 150, 151, IGO, 161). 



Genus 32. — Acroura, Agassiz (Vol. II, p. 152). 



Disc small, arms long and slender, supporting on their lateral borders small scales. 

 Range of genus from the Trias to Lias. One British Liassic species (Vol. II, p. 153). 



Genus 33. — Amphiura, i^or(5es (Vol. II, p. 15S). 



Disc small, orbicular ; upper surface covered with smooth small scales, the six central 

 plates forming a rosette. Arms long, covered with scales, and exhibiting on the margins 

 simple lanceolate spines. Range of genus from the Oolitic strata to existing period. 

 One British Oolitic species (Vol. II, p. 158). 



Section C. — Two genital fissures on each interbrachial s^jace. Disc membranous and 



naked. 



The section ranging from the Silurian strata to the existing period is represented by 

 one British Oolitic genus (Ophiurella) and two species. 



Genus 34. — Ophiurella, Agassiz (Vol. II, p. 154). 



Disc small, membranous. Arms long and slender, bearing on the lateral margins 

 elongated filiform spines. Genus found in the Oolitic strata. Two British Oolitic species 

 (Vol. I, pp. 154, 156). 



