A. E. Verrill — Corals of the Genus Acropora. 239 



Six septa arc well developed and form a regular star in all the cal- 

 icles, the directives being wider. In many calicles six very narrow 

 septa of the second cycle are visible. 



The coenenchj^ma is dense and rather closely covered with rather 

 sharp rough granules, often united into linear or irregular groups, 

 and also more or less covering the walls of the corallites on the 

 larger branches. 



Zanzibar, Mus. Yale Univ., type, No. 4;)5. Received from Bos- 

 ton Soc. Nat. History, as a duplicate. 



This species somewhat resembles A. vlrgata (D.), the type of which 

 (No. 2001) I have compared with this. ^1. vlrgata has the larger 

 radial corallites stouter, more ascending, more comj^ressed, obliquely 

 truncated, with a very short inner lip, and more sti'ongly costulate and 

 echinulate walls. The corallites of the larger branches are larger, less 

 squarrose, more prominent. Its coenenchyma is more strongly and 

 more roughly sj^inulose. 



Acropora tubigera (Horn). See p. 319. 



Madrepora tubigera Horn, Proc. Acad. Nat. Sci., PhilacT., 1860, p. 435 (non 

 Qnelch, nee Brook). 



Plate XXXVI. Figures 1, 2-2b. Plate XXXVI A. Figures 1, 2, 2a, 2b. 

 Plate XXXVI F. Figure 8. 



Horn's type, in the Mus. Phil. Acad, of Science, was carefully 

 examined hj me, many years ago, and described in my notes. Sev- 

 eral fine specimens now in the Museum of Yale University and Mus. 

 Comp. Zoology, from Singapore, were identified by me, at that time 

 (1863), by direct comparison with the type. 



It is a common Singapore species. Many specimens were brought 

 from there about 1860 to 1863, by Capt. W. H. A. Putnam, during 

 several voj\ages to that port. These are now in the Museum of 

 Comp. Zoology; the Peabody Inst., Salem, Mass.; and the Yale 

 Museum. Altogether I have seen about 20 specimens of it. 



It forms somewhat irregular rounded or one-sided, much branched, 

 convex clumps, up to 12 to 15 inches (300-3*75™") across, and 4 to 8 

 inches (100-200™™) or more in height, with the proliferous terminal, 

 upright branchlets rather slender, tapered, subacute, and usually ter- 

 minated by a slender exsert axial corallite. 



The texture of the coral is firm, dense, almost translucent, with 

 few pores, and the surface of the coenenchyma is generally vermicu- 

 lated or irregularly pitted, sometimes costulate, and rough with more 

 or less numerous spinulose granules. 



