208 KKCKNT MAUKKI'OKAUIA OF TIIK HAWAIIAN ISLANDS AND LAYSAN. 



At one jilacv seven layers, (iiie above another, can be recognized, each one of these being separateil 

 from the one beneath by a hiyer of epitheca. 



The caUces are f-inall and are separated by tliick, jiorons walls, wliich may be 0.5 to O.S mm. or 

 even 1 mm. thick, but l>ecome acnte at the edge. 



The twelve septa extend for an ei|iial distance into the calicnlar cavity. They are nearly solid, 

 show 2-3 rough teeth, and especially lateral sjiines that are elongated down in the calice and at ita 

 l)Ottom build a ring joining the ends of the septa together. From this structure a trabecular columella 

 may be develojied. Often the septa are fused together in pairs. 



Pali six in number; in some cali(!es more, in others less developed. The calices are not of the 

 same size: on the hillocks larger, hexagonal, and 1.3 to l.S mm. in diameter; in the valleys smaller, 

 often deformed, 1 nun. in diameter. The depth is small, scarcely 1 to 1.3 mm. 



As the interseptal loculi are narrow, and iis they are soon filled up by the synapticula between 

 the septa, and the pores in both the walls and the septa are relatively .small, the whole corallum has 

 a compatrt, dense structure. 



A piece that has been .saweil from a specimen from Laysan ajjpears, according to the structure of 

 its calices, to belong to same species. It was a part of a massive corallum, whose upper surface shows 

 a large number of laterally compressed elevations, 10 to 18 mm. high and 15 to 20 mm. in diameter. 

 This specimen does not consist of layers one above another, but the section, 10 cm. wide and 20 cm. 

 long, is homogeneous; only the still living portion can be separated from the dead, inner, white mass 

 as a brown superficial layer 4 to 7 mm. in thickness. Toward the apex of the specimen the living 

 layer is as nuich as 11 mm. thick. On one place near the base the living portion has been lifted 

 above the underlying layer for a short distance and has built a thick epitheca on its underside. 



This form is nearly related to J'.jjitrrlsleUnta Quelch (Challenger Reef Corals, p. 187), which it also 

 resembles in habitus. 



In this [Quelch's] .specie.s, however, the columella appears always to be absent and the calices 

 seem to be deep. 



P. califomica, Verrill, Trans. Connecticut Acad. Arts Sc, Vol. I, Part 2, 1867-1871, p. 504, also 

 may be closely related; at least Verrill's description indicates a similar form. 



Hawaii, Molokai. 



Memarks. — Professor Studer has had the kindness to send me a photograph of 

 this species. I can therefore add a few notes to tho.se given by him. The septal 

 formula is simihir to that of P. hlxita, the dor.sal solitar}- directive, the four lateral 

 pairs and the members of the ventral triplet with their inner ends not fused into a 

 group, although united by the ring of palar .synapticula. The wall appears to be 

 constituted as in /'. lohata; but they do not seem to be the same, as the skeletal parts 

 of P. (juilclii are thicker, the wall wider and more dense, the cohimella more com- 

 pact, and the usual niimboi-<if ]ia1i six. whereas in P. lohata eight is the usual number. 



8. PORITES BRIGHAMI. new species. 

 Plate l.XXXIV, figs. 3, 3a. 



The coralluiii of th<' i\\w specinu'n is attaclien, epithecate ainiiii(l the edge. The 

 upper surface is flattened; sides .siimou.s. Dimensions, about tio mm. long; 43 mm. 

 wide; 1.5 nmi. thick. 



Calices deep, funnel shaped, polygonal in outline, usual diameter, 1.2 mm. 

 The wall is slightly el(>vated above the siunmit of the septa, thin, and interrupted. 

 Tlie .septa are distally much tliickeiied and are joined together very near the wall by 

 a circle of .-iynapticula, tlms forming a thick, almost compact mural apparatus. 



The septid arrangement is a dor.sal directive, four lateral pairs, and a directive 

 triplet: in the triplet, the inner ends of the laterals approach the ventral directive 



