202 PAPERS FROM THE DEPARTMENT OF MARINE BIOLOGY. 



most species of the genus. Except on the structures mentioned, there is relatively little 

 granulation of the skeletal surfaces. 



Station, Murray Island. — Southeast reef, line I, i,6oo feet from shore; water 

 lo inches deep. 



Distribution. — Murray Island. 



13. Porites pukoensis Vaughan. 

 Plate 90, figs. I, ifl, i^, specimen from Fanning Island; figure 2, calices ot a paratype from the Hawaiian Islands. 



1907. Porites pukoensis Vaughan, U. S. Nat. Mils. Bull. 59, p. 195, plate 94, plate 95, figs, i, 2. 



In order to make a proper comparison with the specimen collected by Mr. C. 

 Elschner at Fanning Island, it is necessary to quote my original description and 

 notes on the suite of specimens from the Hawaiian Islands: 



"Corallum forming thick, irregular, compressed or subterete, nodose columns, on which 

 humps or stumpy protuberances may occur. The columns rise from a common base, and 

 are more or less fused throughout their length, except the free projecting ends, or in some 

 instances they are fused both above and below, leaving intermediate open spaces. Two 

 views, natural size of the type specimen, sliovving the habitus and size of the corallum, are 

 given on plates xciv, xcv. There are three other specimens: The largest is of nearly the 

 same size as the type, the columns distally diverge more, their ends are truncate, and some 

 of them are more compressed. One of the other specimens is young, incrusting a branch 

 of a species of PoriUs and sending up columns from 24 to .|2 mm. in height, tapering to 

 rounded or truncate ends. The fourth specimen is composed of several lobes, tapering to 

 rounded ends, and a twisted, truncate plate, all rising from a common base. It shows no 

 notable difference from the third specimen. 



"Calices polygonal, excavated, rather deep, diameter from 1.25 to 1.5 mm.; separated 

 by elevated, simple, perforate walls. Mural denticles rather tall, minutely frosted, about 

 twice as many to a calice as there are septa. 



"The septa usually begin a slight distance below the upper edge of the wall. Between 

 a palus and the wall, there is usually a single septal trabecula, terminating above in a septal 

 granule, usually not prominent, and slightly detached from the vvall. Rough radial denticles 

 may be present on both the mural and septal trabeculae. There is an incomplete peripheral 

 ring of synapticula, no distinct mural shelf. Septal faces frosted, often rather densely and 

 coarsely; interseptal loculi not very wide, frequently tend to be decidedly narrow, and may 

 appear closed. 



"Pali tall, slender, more or less lath-like; the formula complete; joined by a complete 

 ring of synapticula. 



"Columella tall, a narrow lamella, joined by thick radii to the inner ends of the septal 

 groups. 



"Locality. — Pukoo, Molokai; two specimens collected by Dr. J. E. Duerden; i specimen, 

 also collected by Doctor Duerden, the locality label has been lost, but it probably comes from 

 the same locality; i specimen, received from Dr. W. T. Brigham. 



******* 



"The calicular characters of P. pukoensis are practically identical with those of P. com- 

 pressa forma angustisepta. As was remarked in discussing the latter form, it is not at all 

 unlikely that they may be only different growth-forms of the same species. However, the 

 specimens at my disposal for study do not show intergradation. 



"P. lobata forma parvicalyx (p. 200) is also closely related. It forms thicker columns, 

 and its calices are smaller. The walls of the two are similar, but usually they are taller in 

 P. lobata forma parvicalyx. Neither of the extreme conditions was seen in the calices of P. 

 pukoensis. The septal granules of the latter are not so tall and are not so far removed 

 from the wall; the pali are constantly present and the columella tangle does not become 

 an indefinite mesh-work. 



"The three forms, P. compressa forma angustisepta , P. pukoensis, and P. lobata forma 

 parvicalyx constitute a most interesting series. It may be that they all belong to the same 

 species. Should they do so, they will show that the growth-form of corals is of only slight 

 systematic importance." 



