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



Even in 1864, I had devoted over three years to the continuous 

 study of reef-corals, including all of Dana's types, so that I was 

 then very familiar with all his species, and not more likely to err 

 than now, in comparing types. 



A. canalis Quelch, sp. (op. cit., p. 150, pi. ix, fig. 2), from the 

 Philippines, is a very closely allied species, and perhaps will not 

 prove to be distinct, when a series from that locality can be studied. 



Brook refers the latter (with ndbilis) to his subgenus Tylopora, on 

 account of the large, thick-walled axial corallites. This character is 

 as variable as others, and I think that Brook has given it too much 

 importance in many cases, thus widely separating species that are 

 closely allied, and perhaps, in some instances, widely separating 

 forms that are mere varieties of a single species, as in the case of 

 seeunda and nobilis. To me this species seems to be more nearly 

 allied to typical Eumadrepora. 



Acropora pachycyathus Ver., sp. nov. 



Plate XXXVI. Figure 20. Plate XXXVI C. Figure 5. 



Plate XXXVI F. Figure 6. 



Coral probably caespitose, perhaps corymbose. Branches diver" 

 gent, stout, 20--25 mm in diameter, often irregularly proliferous ; the 

 terminal branchlets short, tapered, obtuse. 



Axial corallites large and swollen, (4-5 mm in diameter), with thick, 

 rounded, porous walls and a rather large, deep calicle, 2 mm in diame- 

 ter. They are about 2-4 mm exsert. 



Radial corallites large, thick, unequal in size, ascending, laterally 

 sessile, very irregularly arranged, often aggregated into uneven and 

 prominent clusters. The larger ones are mostly tubular, or conic- 

 tubular, with stout, enlarged bases and thick, swollen, incurved sum- 

 mits ; their small calicles open obliquely inward, so as not to be 

 visible in a side view. But with these are some that are more regu- 

 larly tubular, truncate at the blunt ends, with the calicle round and 

 terminal ; some of these may carry basal buds and eventually 

 become axial corallites. They are from 3 to 5 mm long and 3 to :;..V nm in 

 diameter. They are mostly attached for the whole length of the 

 inner side, but not appressed. The inner lip is usually very short or 

 absent, but may be fairly well developed. The aperture is very 

 small (0.6 to l mm ) and often is almost concealed by the very thick, 

 rounded outer lip, which usually curves inward very strongly. On 

 the distal part of the branchlets they are more regular in form and 



