206 KKCENT MADKKl'OKAKIA OK THE HAWAIIAN ISLANDS AND LAYSAN. 



fuiTdws. oil)lK)sitie.s, tiiid lobes; on the upper surface thick, obtusely rounded crests 

 and lobes? Tlie crests are from lu to lt> nun. thick; uiaximum height 16 mm.; the 

 thickest lobe lias a diameter of '23 mm.; height 20 mm. The base of the specimen 

 is dead and was ])art of an older coralhuii; between the broken-off piece of the dead 

 coralhun and the living portion is a constriction. Total height, including dead base, 



1 !."> nun. : niaxinnun (K'jith of living portion, 66.5 mm.; greater diameter in constric- 

 tion, 65 mm.: lesser, 43; greatest diameter above the constriction, 99 mm., lesser, 



81 nun. 



Calices polygonal, excavated, and moderately deep. Diameter from 1 mm. to 



2 mm. Much smaller in the concavities; larger on the convexities, where they 

 avi'rage al)out 1.6 nun. Separated by rather thin, somewhat elevated, perforated 

 walls, on whose sunnnits are about twice as many frosted mural denticles as there 

 are septa to a calicc. 



Septa with the inner ends of the triplet not fused together. Palar formula com- 

 plete. Between a pains and the wall usually two frosted granules, sometimes only 

 one. Tali not very tall or thick, frosted. Two synapticular rings, the outer rather 

 thick and more or less connected with the wall; the inner joining the pali. A septal 

 granule is usually either above or just interior to the outer ring; therefore, there is 

 a more or less distinct nuiral shelf. The septa are rather thick, with frosted sides; 

 interseptal loculi almost closed. 



Columella a deli<;ate, compressed, frosted tubercle, situated in a pit, surrounded 

 l)y the perpendiculai- inner edges of the pali, joined to the inner ends of the septal 

 groups by radii. 



Locality. — Kancnlii-. Oalm. Pi'of. .1. E. Duerdcn, collector. 



PORITES LOBATA forma APERTA, new. 



Three specimens of this I'orma are described: two from Pukoo, Molokai, 

 received from Dr. ^V. T. Brigham, and one from Waikiki, Oahu, collected by 

 Prof. J. E. Ducrden. One of the sy)ecimens from Pukoo is young and shows the 

 early mode of growth; the other probably represents the adult condition; thej^ will 

 be used a.s eotypes. 



The coi'allum of the younger specimen is composed of successive caps, otie above 

 another, in contact or continuous in growth in the central portion, but around the 

 edges the}' are distant and have the lower surfaces invested by epitheca, nuUipores, 

 etc. The layers are not thick, about 5 mm., thinner on the margins. Greater diam- 

 eter of base, 97 nun.; lesser, 79; height, 59. The upper surface is thrown into 

 irregular, thick Immiis of various sizes, the tallest about 21 mm. The other speci- 

 men is a thick lobe, with a corroded base, evidently derived from the outside of a 

 coralhun. (ireater transverse diameter, 97 mm.; lesser, near base, 50 mm. Out- 

 side with several deep, longitudinal depressions, and intervening tall, rounded ridges; 

 sunuuit truncate. Th(^ calicular structure of both these specimens is the same, and 

 the set-ond could be derived from the first by the upward growth of one of the laigcr 

 humps. 



The remainder of the description will be based on the second specimen. 



