BRAZILIAN ASTRA MUD CORALS— V A VGHAN. 



849 



more isolated than in the latter; the septa of the latter are stouter. 

 A. rafhhun! (the second Brazilian .i,v/;r^w/;^/) rosrmhlo< .(. solUarla 

 in iiahitus more than does ^1. l)r((siIle)tH/!<. 



ASTRANGIA RATHBUNI, new species. 

 Plate l.XXVIir. 



Coralluni iiu-rustino-, attached to objects of various .^^hape.s, often 

 forniino- small, rounded clumps. 'V\\o coraHit(\s are r.ot crowded, and 

 are more or less tufted. Reproduction l)y basal expansions, which are 

 frequently stoloniferous in character, occasionally by lateral genuna- 

 tion. Sometimes there appear to be shreds of epitheca around the 

 corallites. 



The corallites are rather tall, as much as T mm., but 4 nun. is prob- 

 ably an averaj^e. The calices are rather laroe. The measurements of 

 3 are as follows: 



The cost* of the corallites are indistinct, except just l)elow the calic- 

 ular margin, where they are small, but show a recognizable alterna- 

 tion of larger and smaller. 



The septal margins project very slightly a))ove the upper edge of 

 the corallite wall; the septa are thin ai.d narrow above the bottom of 

 the calicular fossa. In the larger corallites there are four complete 

 cycles. The members of the first and second eyeries reach the columella, 

 those of the third cycle usually l)end toward the memljers of the 

 second, and those of the fourth toward the members of tlie third. Tlie 

 margin of all septa are dentate, the dentations fre(iuently truncated, 

 sometimes showing secondary dentations on the inner edge, but not 

 in the sinus between dentations. Paliform lobes are not distinctly 

 ditierentiated. The calicular fossa is very deep. The columella is 

 weak and is papillary above. 



LmxiUt/(^s.—Vin\iietii, Rio ,Taneiro, and Bay of Rio Janeiro, Brazil. 



Ti/pe sjjeri/uen.—F'dqueta, Rio Janeiro (No. 1(1974, U. S. Nat. Mus.). 

 Collected by Richard Rathbun, Geological Commission of Brazil, 1877. 

 There are eight specimens in all. 



liimcn-h^.— The most nearly related recent species of the West 

 Indian region is Astrangia astreifomilx M. Edwards and Haime. The 

 corallites of this i^ecies are more intimately united one to another, 

 Proc. N. M. vol. XXX— 06 54 



