A. E. Verritt — Corals of the Genus Acropora. 258 



Acropora armata Ver. 



Madrepora armata Brook, op. cit., Ann. and Mag. N. Hist., x, p. 452, 1892. 

 Catal. Mad., p. 100, pi. x, figs. A, B, 1893 (?=A. turbinata Ver.). 



Mr. Brook considered the coral figured by Dana as variety of his 

 spicifera (p. 443, pi. 31, figs. 6-6c, pi. 33, figs. 4-45) identical with 

 his armata. 



This does not seem to be the case. 



The type of Dana's variety is in the Museum of Yale Univ., No. 

 2007. It differs in the details of the corallites and coenenchyma, 

 though it grows in similar form. It also resembles A. turbinata 

 in its mode of growth, but it has much smaller calicles than the 

 latter, the walls and coenenchyma are much less porous, and the 

 outer lip is narrower and more ascending. 



A. turbinata agrees, therefore, very closely with A. armata and 

 is probably identical with it, for the latter has the same spreading 

 radial corallites and very porous and fragile lower lip as turbinata. 

 But Dana's variety has an ascending or almost appressed outer lip, 

 which is compact and strong, though thin, and the corallites and cali- 

 cles are decidedly smaller. I propose to call the latter A. cytherella. 



Acropora cytherella Ver., sp. nov. 



Madrepora spicifera (var.) Dana, Zooph., p. 443, pi. xxxi, figs. 6-6c, pi. xxxiii, 

 figs. 4-46. 



Plate XXXVI. Figure 7. Plate XXXVI A. Figure 7. 



Plate XXXH F. Figure 1. 



The coral is vase-shape or salver form, from a stout pedicel, and 

 the under surface of the coalesced branches is covered with diver- 

 gent calicles and dwarfed branchlets in the type, as figured by Dana. 



The branches of the upper side are slender and very proliferous 

 distally, mostly 25 to 35 mm long. The axial corallites are about 2 mm 

 in diameter and 2-3 mm exsert, cylindrical, with firm, finely and 

 regularly costulate walls. 



Radial corallites dimidiate-tubular, elongate, 2-3 mm , strongly 

 ascending, not truly appressed; outer lip long, thin, but not fragile, 

 half-round, with the aperture very oblique ; inner lip thin, often 

 free to some extent, but mostly adnate ; wall finely and regularly 

 costulate with a few very small pores in the grooves. Coenenchyma 

 irregularly and roughly pitted, and spinulose, rather firm. 



Calicles small, 0.5 to 0.8 mm . Septa distinct, but narrow, in the 

 axial corallites, usually 6, sometimes 12 ; all nearly abortive in the 

 radial calicles. 



