4G BRITISH PALAEOZOIC ASTEROZOA. 



Stiirtz, Palxnectria devonica, Stiirtz, ISalteraster (Paheaster) asperrimus, Salter, Hisingeraster 

 (Palasterino) antiqua, Trentonaster {Palasterliia) sfeUofa, Billings, Palasterina prim>eva, Forbes. 



2. Encrinasteri^-Cryptozonia, including Pseudopalasterlna (Palasterina) folhnanni, Stiirtz, 

 Palasteriseus devonicus, Stiirtz, Palieosolaster gregoryi, Stiirtz, Palieocoma marstoni, Salter, P. colvini, 

 Salter, P. cygnipes, Salter, Bdellacoma vermiformis, Salter, Rliopalocoma, pyrotechnica, Salter, 

 Loriolastei- mirabilis, Stiirtz, Cheiropteraster gigantens, Stiirtz. 



3. Eustellerid^-Phanerozonia, including Xtnaster simplex, Simouow., X. margarltatus, 

 Simonow., Astrnpecten schliiteri, Stiirtz. 



4. EusTELLERiDiE-CRYPTOZONiA, including Lepidaster grayl, Forbes, Roemeraster asperula, Eiiui.- 

 Stiirtz, Asferias aciiminatus, Simonow., Jaekelaster petaliformis, Stiii'tz, Ecliinaslerella sladeni, Stiirtz, 

 Echinasteria.s spinosiis, Stiirtz, Echinodiscus multidactylus, Stiirtz, EcJiiiiosfella traquLiiri, Stiirtz, 

 Mednsasfer rhenanus, Stiirtz, Profasteracanthio)i primus, Stiirtz. 



Stiirtz thought that lie couhl establisli a near relationship between these 

 Palaeozoic forms and certain Recent genera, and the table given 80, p]). 200 — 208. 

 summarises his views on this point. 



Gregory in 1899 (27) proposed to abandon the classification of Bronn, for, as 

 he rightly observed, the character is difficult to nse. " In some starfi.shes the 

 ambulacral ossicles in one part of a ray may be alternate, while in another part 

 they may be opposite." 



Gregory preferred to rely upon Sladeji's classification into Phanerozonia and 

 Cryptozonia, and regarded the alternation of the ambulacralia as a primitive 

 character which could be found in early members of both these groups. 



Gregory's classification is as follows : 



Order 1. PHANEROZONIA. 



Family 1. Palseasteridse. 



Phanerozonia with the ambulacral ossicles all or mostly alternate in position. The 

 niadreporite is aliactinal, and the oral armature adambulacral. The skeleton of the 

 abactiual surface and interradial areas is tessellate. Marginal plates large. 



Snl)-fami]y 1. Palaeasteriuse. 



Palaeasteridffi with the ambulacral ossicles definitely alternate. The rays are usually 

 long and sharply marked off from the disc, which is usually small, with interradia 

 areas. Genera: Paheasler, Hall, Argaster, Hall, ? Tetraster, Etheridge, jun., and 

 Nicholson, Petraster, Billings, Monaster, Etheridge, jun., pars. 



Sub-family 2. Xenasterinse. 



Palseasteridis with the general characters of the Pateasteringe, but witli most of the 

 ambulacral ossicles opposite. Genus : Xenaster, Simonowitsch. 



Sub Family 3. Lindstromasterinse. 



Palseasteridae with alternate ambulacral ossicles, a large disc covered with tessellate plates, 

 and large interradial areas. Genera: Liudstromaster, Gregory. Uranaster, Gregory. 



Family 2. Palseasterinidae. 



Phanerozonia with the ambulacral ossicles alternate, the oral armature adambulacral, 

 and the madreporite abactiual. The disc is large and pentagonal, and the rays are 

 short and separated by large interradial areas. The marginal plates are smaller than 



