A. E. Verrill — Corals of the Genus Acropora. 237 



arrangement, with the end truncate and tlie nearly round calicle 

 opening upward. 



Among the larger radial calicles are many that are smaller, shorter, 

 conoidal or verruciform, with a very small terminal calicle, often 

 less than 0.5'"'" in diameter. No entirely immersed calicles occur on 

 these branches. 



Septa of the axial corallites 12, those of the 1st cycle well devel- 

 oped, the others narrower. In the radial corallites six are wide and 

 six very narrow, but distinct. 



Surface of walls and ca'nenchyma everywhere rather coarsely and 

 roughly echinulate ; tire granules on the distal corallites usually 

 thorny or lacerate, not crowded, often in costal lines, but no costulae 

 are visible. The coenenchyma is dense. 



The type (No. 6141) is a single branch with four principal divis- 

 ions and several small, distal, divergent branchlets. 



Locality unknown (coll. Ward). Perhaps the rest of the speci- 

 men may be in the Field Columbian Museum. 



This species is remarkable for the large, very thick-walled, closely 

 adherent radial calicles, having the small apertures mostly concealed 

 in a side view, by the very swollen, incurved outer lip. 



It belongs to the group Tylostoma, in Brook's system, on account 

 of the large and swollen axial corallites, but it does not have much 

 resemblance to any other species of that group. Perhaps, in general 

 appearance, it is more like .1. (joncif/ra tlian any other species. 



Acropora prolixa Yer. See p. 217. 



Madrepora prolixa Ver., Communications Essex Inst., Salem, vol. v, p. 22, 

 1866. Brook, op. cit., p. 187. 



Plate XXXVI. Figures 3, 3n. Plate XXXVI A. Figures 8, 8a. 



Plate XXXVI F. Figure 14. 



Mr. Brook (p. 187) referred this species doubtfully to his M.longi- 

 cyathus (E. & II.), which he redescribed from the type. 



Our species does not agree with his description, nor with an 

 authentic fragment of the type of Edw. & Haime, sent to the 

 Mus. of Comp. Zoology, by Prof. Milne-EdAvards himself, and with 

 which I had compared my type, in 1864, as then stated.* 



* Mr. Brook, in numerous instances, ignored the fact that I have had constant 

 access to the types of Dana and others and that my determinations of species 

 were made by comparison with types. Thus he often arrived at different 

 and erroneous results. Had he kept this fact in mind, and given it due weight, 

 he might have avoided several errors. 



