DESCRIPTIONS OP SPECIES. 155 



reserved by Oken for this latter section, without doubt because the species 

 called by Ellis Madrepora galaxca was the Madrepora astroites of Limifeus.''^ 

 In 1830 de Blainville" renamed the Astrea Lamarck (pars) (=Astrfea Oken) 

 Siderastrea. Quelch, in his report on the Challenger Expedition reef corals, 

 considers that Oken had no right to take Madrepora galaxea Ell. and Sol. 

 as the type of Astrea, but that Astrea rotulosa should be the type, and he 

 places Favia, proposed by Oken for the latter species, in the synonymy of 

 Astrea, and uses Siderastrea for the Madrepora galaxea group of species. 

 Gregory, the last to consider the subject, supports the conclusion of Milne- 

 Edwards and Haime, but notes the use of Astrsea previous to the time of 



Lamarck. 



The name Astrea, for reasons already given, must be abandoned. 

 Oken had a perfect right to subdivide the Lamarckian genus; therefore his 

 name Favia must stand for the Madrepora rotulosa group of species. The 

 Madrepora qalaxea is thus left without a generic designation. The first 

 name proposed after Oken was Siderastrea, by de Blainville, and this must 

 stand. Siderina of Dana falls into the synonymy of Siderastrea. 



This name Astrea has been a source of so much trouble to students of 

 zoophytes that it is truly fortunate that strict laws of nomenclature compel 



us to abandon it. 



It is not necessary to enter into a discussion of the stractural features 

 of the genus, as the work of Miss Ogilvie^ is sufficient. 

 Siderastrea hexagonalis sp. uov. 

 PI. XVIII, figs. 1 to 4. 

 . 1894. Sidermtrcm hexagonalis Vaugl.an noui. nud. Rept. geol. Coast. PI. Ala.: Ala. 

 Geol. Survey, 1894, p. 248. 

 Corallum massive, depressed, with flat base. Greatest distance across 

 type specimen, 57 mm. ; thickness, 23 mm. Greatest diameter of calices, 6 

 to 7 5 mm. Corallites hexagonal, separated by a thin wall of synapticular 

 composition. The wall is usually slightly raised. The septa -of adjoining 

 calices may meet each other end to end, or they may alteraate in position. 

 Septa do not show a very defi nite cyclical airangement; in one calice 68 



■ Milne-Edwards and Haime, Hist. Nat. des Corall., loc. oit. 



3?iS;fe1n h?r nlros'^and s'!;. Stud. Mad. Types of Corals, 1896, p. 159, makes some remarks 

 on Astrea, but she shows an absolute ignorance of the history of the name; so her notes need no 



discussion. 



nbid., pp. 178-183. 



