Genera of Recent Clypeastroids. 605 



Arachxoides, Leske, 1778. Add. ad Klein, pp. 8 & 154. T^'pe, Arach- 

 noides echinarachnius, Leske, I. c.,= Ec/mius placenta, Ijiuiii, 1758, 

 Syst. Nat. ed. 10, p. 666. Monotypic. 



Laganum, Gray, 3825. Ann. Phil. x. p. 5 {Lagana, by error). Type, 

 Echinodiscus laganum, Leske, 1778, Add. ad Klein, p. 140,= 

 Laganum bonani, Agassiz, 1841, and later writers. Type by 

 tautonomy. 



Peroxella, Gray, 1855. Cat. Recent Ech. pt. i. p. 13. Type, Laganum 

 2}efonu, Agassiz, 1841, Mon. Scut. p. 123. Monotypic. Proposed 

 as a subgenus. 



Fibularia, Lamarck, 1816. Anim. s. Vert. iii. p. 16. Type, Fibularia 

 trigona, Lamarck, /. c,, = Echinocgajtins craniolaris, Leske, 1778, 

 Add. ad Klein, p. 150. Type fixed by elimination by Agassiz 

 and Desor, 1847, Ann. Sci."^ Nat. (3) vii. p. 142. Since Agassiz 

 and Desor's work permits either trigona or ovulum to be the type, 

 I will designate the former, although I have no doubt both are 

 synonyms of Leske's Echinocyamus craniolaris. 



EcHixocYAMUs, Leske, 1778. Add. ad Klein, p. 149. Type, Echino- 

 cyamus angulosus, Leske, op. cit. p. 151, = Echinus 7ninutus. Pallas, 

 1774, Spic. Zool. X. (usually quoted erroneously as ix.) p. 34, pi. i. 

 fig. 25, as delimited by Leske, op. cit. pp. 150-152. Type fixed by 

 elimination by Agassiz and Desor, 1847, Ann. Sci. Nat. (3) vii. 

 p. 140. 



Alexaxdria, Pfeffer, 1881. Verhandl. Naturw, Ver. Hamburg von 

 1880, p. 63. Type, Alexandria magnijica, Pfeffer, op. cit. p. 64. 

 Monotypic. 



ScuTELLA, Lamarck, 1816. Anim. s. Vert. iii. p. 7. Type, Echinodiscus 

 subrotmidus, Leske, 1778, Add. ad Klein, p. 142. Type fixed by 

 elimination by Agassiz, 1841, Mon. Scut. p. 76. 



EcHiXARACHXius, Gray, 1825. Ann. Phil. x. p. 6. Type, Scutella 

 parma, Lamarck, 1816, Anim. s. Vert. iii. p. 11. Type fixed by 

 elimination by Agassiz, 1841, Mon. Scut. p. 89. 



Dexdrastek, Agassiz and Desor, 1847. Ann. Sci, Nat. (3) vii. p. 135. 

 Type, Scutella e.vcentrica, Eschscholtz, 1831, Zool. Atlas, p. 19. 

 Monotypic. 



EcHixoDiscus, Leske, 1778. Add. ad Klein, p. 131. Type, Echino- 

 discus bisperforatus, Leske, op. cit. p. 132. Type limited by 

 Agassiz, 1841, Mon. Scut. p. 62 (under name Lobophora), to either 

 bisperforatus, auritus, or inauritus of Leske, and the first, in the 

 form of its second variety, has been selected by me in the present 

 paper, p. 597. 



AsTRiCLYPEt'S, Verrill, 1867. Trans. Conn. Acad. i. p. 311. Type, 

 Astriclypeus manni, Verrill, /. c. Monotypic. 



EucoPE, Agassiz, 1841. Mon. Scut. p. 45. Type, Echiiiodiscus emar- 

 ginatus, Leske, 1778, Add. ad Klein, p. 136. Type fixed in the 

 present paper, p. 599. 



Mellita, Agassiz, 1841. Mon. Scut. p. 34. Type, Echinodiscus quin- 

 quiesperforatus, Leske, 1778, Add. ad Klein, p. 133, Type fixed 

 in the present paper, p. 599. 



RoTULA, Agassiz, 1841. Mon. Scut. p. 23. Type, Echinus orbiculus, 

 Linn^, 1758, Syst. Nat. ed. 10, p. 266, as delimited by Leske, 

 1778, Add. ad Klein, pp. 133, 144, l'l(j,=Rotula rumphii, Agassiz, 

 1841, and later writers. Type by virtual tautonomy. 



Cambridge, M.iss., 

 March 1911. 



