GEKERA AND GROUPS OP THE ECHTN"OrDEA. 231 



Leueaster, Gauthier, 1887, Bull. Soc. d. Sci. Hisfc. et Nat. de 

 I'Tonne, vol. 41 e (pub. 1888), p. 386, is a Hemiaster with very 

 small pores in the anterior zone of the antero-lateral ambulacra 

 near the apes. 



Perionaster, Gauthier, 1887, ibid. p. 389. The type is a very 

 small immature Hemiaster, with a remarkably developed peri- 

 petalous faseiole, see H. expergitus, Loven. 



Type I. — Fossil. Cretaceous: England, Europe, -N. Africa, 

 Arabia, Hindostan, IST. and S. ; N. America ? 



Becent. E. Atlantic; W. of Spain; Caribbean Is., 464-485 

 fms. ; Bahia ; Canaries, 620-750 fms. ; Japan ; Arafura Sea, 345- 

 800 fms. 



Type II. — Fossil. Tertiary : England, Europe, "W. Indies, N. 

 Africa, Egypt, Asia, Sind ; Australia ? ; Java, N. America. 



Becent. S. Hemisphere, Patagonia, Chili, Magellan, La Plata 

 coast, Kerguelen, Heard Is., Staten Land, South Polar Seas. 



Subgenus Triptlus, Philippi, 1845 ; Troschel, 1851 (genus), divi- 

 sion Hamasitus, Wiegm. Arch. 1851, p. 72. 



Syn. Ahatus, Troschel. 



Hemiasters with two genital pores in the female and three in 

 the male, the apical system Ethmolysian, may have a fifth basal ; 

 peripetalous faseiole (around petaloid ambulacra deeply sunken 

 in the female) ; a slender latero-anal faseiole, which may be in- 

 complete. Type T. ecccavatus, Phil. 



Becent : Patagonia and Chili. 



Genus Faorina, Gray, 1851, Ann. Sf Mag. Nat. Hist. vol. vii. 



p. 132 ; 1855, Cat. Bee. FcJi. Brit. Mus. pt. i. p. 56 (pars). 



A. Agassiz, 1872-74, Bevision, pp. 129, 607. Loven, 1874, 



Etudes, pi. xxvii. 



Test moderate in size, broadly cordiform in outline, grooved in 



front, narrower and truncated posteriorly, high and subconical. 



The vertex is central. 



Apical system excentric in front, with four basal plates, two 

 of which, or sometimes three, are perforated ; madreporite pro- 

 jecting backwards. 



Ambulacra dissimilar, the anterior in the groove with minute 

 pairs of pores abactinally, and larger and more distinct actinally ; 

 the autero-lateral straight, sunken, divergent, open distally, the 

 pairs of pores indistinct near the apex and elsewhere large and 



