ASTEROIDEA. 



191 



Slad. ; Culcita L. Ag. ; Asterodiscua Gray ; Choriaster Liitken ; Paulia 

 Gray. 



Fam. 7. Gymnasteriidae. Marginal plates large. The whole body is 

 covered with a thick membrane. Arms usually short. Actinal inter- 

 radial areas with large regular plates. Abactinal skeleton tesselate. Anus 

 distinct. Asteropsis M. and T. ; Dermasterias Perr. ; Gymnasterias Gray ; 

 Tylaster D. and K. ; Porania Gray (Fig. 138) ; Marginaster Perr. ; 

 Rhegaster Slad. ; Poraniomorpha D. and K. ; Lasiaster Slad. British 

 species : Porania pulvillus. E. N. AtL, to 106 fms. 



Fam. 8. Asterinidae. With small, sometimes inconspicuous marginal 

 plates. Abactinal skeleton composed of imbricating plates notched on 

 one side and bearing spines on the free margin. Actinal interradial 

 areas with imbricating plates bearing spines. No pedicellariae. 



Cycethra J. Bell ; Ganeria Gray ; Patiria Gray ; Nepanthia Gray ; 

 Asterina Nardo ; Disasterina Perr. ; Palmipes Linck ; Stegnaster Slad ; 

 Tremaster Verr. British species : Asterina gibbosa, E. N. AtL, to 35 fms. 

 Palmipes placenta, shores of Britain, etc., to 30 fms. 



Sub-Order 2. CRYPTOZONIA. 



Marginal plates inconspicuous. The supra- and infra-marginal plates 

 are often separated by intermediate plates. Papulae not confined to the 

 area bounded by the supra-marginals, but found also between the mar- 

 ginals and on the ambulacral surface. Ambulacral plates crowded and 

 narrow. Tube-feet often in four rows. Ambulacrals or adambulacrals 

 of the oral skeleton prominent. Pedicellariae stalked or sessile. 



Fam. 1. Linckiidae. Marginal plates comparatively well developed, 

 and in contact. Disc small, arms long. Abactinal skeleton tesselate. 

 Pedicellariae (rarely present) excavate or foraminate. 



Chaetaster M. and T. ; Fromia Gray ; Ferdina Gray ; Ophidiaster Ag. ; 

 Pharia Gray ; Leiaster Peters ; Linckia Gray ; Phataria Gray ; Nardoa 

 Gray ; Narcissia Gray ; Metrodira Gray. 



Fam. 2. Zoroasteridae. Marginal plates in contact. Disc small ; 

 arms long, cylindrical, and tapering. Integumentary skeleton spiny. 

 Abactinal skeleton tesselate, arranged in regular longitudinal and trans- 

 verse series. Primary apical plates persistent and distinct in the adult. 

 Tube-feet conical, terminated by a small sucker ; they are arranged in 

 four series at the base of the arm, in two series distally. Pedicellariae 

 (forcipulate) stalked. Zoroaster W. Thorn., for the most part from great 

 depths ; Cnemidaster Slad. ; Pholidaster Slad. ; Mammaster Perr. ; Caly- 

 caster Perr. 



Fam. 3. Stichasteridae. Marginal plates in contact. Disc small ; 

 arms long, cylindrical and tapering. Integumentary skeleton for the 

 most part granular. Abactinal skeleton tesselate arranged in longitu- 

 dinal rows. Primary apical plates less distinct. Tube-feet usually 

 cylindrical and with large terminal sucker, arranged in four rows all 

 along the arms. Pedicellariae forcipiform and forficiform. 



Coelasterias Stimpson ; Stichaster M. and T. ; Tarsaster Slad. ; Neornor- 

 pluister Slad. , Tonia Gray ; Nanaster Perr. ; Granaster Perr. British 

 species : Stichaster roseus, Brit, coast, to 200 fms. 



Fam. 4. Solasteridae. Abactinal skeleton reticulated, with plates 

 carrying on a projecting tubercle a bundle of divergent spines. Actinal 

 intermediate plates more or less developed. Anus distinct. No pedi- 



