ASTEROIDEA. 19 



Asteroidea (pars), Burmeister, Hdbh. Naturg. (1837) p. 467. 



Asteroidea, Wright, Mon. Brit. Foss. Echin. Ouht. ii. (I860) p. 1 ; Nor- 

 man, Ann. fy Mag. xv. (I860) p. 115; Pen-. Arch. Zool. exper. iv. 

 (1875) p. 281 ; Fewkes, Proc. Bost. Soc. N. H. xxiv. (1889) p. 96 ; 

 Sladen, Chall. Rep. Ast. (1889) p. xxviii ; Bell, Ann. §• Mag. viii. 

 (1891) p. 214 ; [non Zittel, in Hdbuch. Pal. (1879)]. 



Stelleridse, Zittel, Hdbuch. Pal. (1879) p. 447. 



Tocastra+Colastra+Brisingastra, Haeckel, Gen. Morph. ii. (1866) 

 pp. lxv & lxvi. 



On the movements of Asteroidea, see Preyer, MT. zool. Stat. Neap, vii, 

 (1886 & 87) pp. 33 & 77 ; on their anatomy see Cuenot, Arch. Zool. exper. 

 v. Suppl. art. 2 (1887-90). 



The Asteroidea are caliculate, actinogonidial, eleutherozoic, azy- 

 gopodous Echinoderms, in which there is an open ambulacral groove. 

 The stellate form of the body is often well marked and the rays 

 prolonged into " arms," which vary in their proportional length to 

 the diameter of the disk ; the digestive system, which is rarely 

 aproctous, and the generative share in the stellate disposition of the 

 organism. Pentameric repetition is more often exceeded in this 

 than in any other class ; and asexual reproduction from a part of 

 the body is by no means uncommon ; respiration diffuse. 



Order 1. PHANEROZONIA. 



Phanerozonia, Sladen, Chall. Rep. -Ast. (1889) p. xxviii. 



Asteroidea with well developed marginal plates in two distinct 

 rows ; the superior and inferior touch, and usually have their axes 

 in parallel planes. Papula? confined within the area bounded at the 

 sides by the superomarginals. Ambulacral plates not crowded 

 nor narrow. Adambulacral plates take a prominent share in the 

 formation of the oral plates. Pedicellarise valvate, foraminate or 

 excavate. 



Family 1. ARCHASTERIDtE. 



Archasteridaa, Viguier, Arch. Zool. exper. vii. (1878) p. 235 ; sens, emend. 

 Sladen, Chall. Rep. Ast. (1889) p. xxviii. 



Phanerozonia in which the calycinal plates are inconspicuous in 

 the adult, the abactinal plates spiniform or paxilliform, and the 

 integument spiny ; there is an anus, no superambulacrals, large 

 adambulacrals, and, usually, pedicellariae. 



Two subfamilies. 



Subfamily 1. PARARCHASTERIX^E. 



PararchasterinaB, Sladen, Chall. Rep. Ast. (1889) p. xxviii. 



Archasteridae with papulae in a limited area only at the base of 



c2 



