172 PAPERS FROM THE DEPARTMENT OF MARINE BIOLOGY. 



zeller's figures 7 and "ja represent the characters of the specimen fairly well. Some 

 of the branchlets are smiilar to his figure Ga. 



Distribution. — According to Brook it is "Red Sea; Rodriguez; Ramesvaram; 

 China Sea; New Holland; Great Barrier Reef; Fiji; Tahiti." I can add Makemo, 

 Paumotus (.ilbatross, 1899-1900), and Fanning Island (Dr. Fred Baker). This is 

 a very widely distributed species. 



Acropora (Polystachis) pectinata (Brook). 

 Plate 71, figures I, la, \b. If, 2, specimens from Murray Island. 

 1893. Madrepora pectinata Brook, Cat. Genus Madrepora, p. 95, plate 27, figs. D, E. 



Dr. Mayer collected two specimens, which I refer to this species: 



Specimen No. i, plate 7/, figs, i, la, ib, ic: 



Corallum attached to dead coral stems by a basal expansion, above the central portion 

 of whicli the principal branches extend more or less horizontally, while the branchlets rise 

 to about the same level; form corymbose. Diameter of basal expansion about 50 by 

 70 mm.; diameter of upper surface of corallum about 95 by 130 mm.; height of corallum, 

 between 55 and 60 mm. Main branches somewhat compressed radially, lesser diameter 

 about 6 mm.; considerable lateral fusion of branchlets, but this small specimen has not 

 formed plates. 



The lower surface of the branches with some protuberant corallites, up to 2.5 mm. tall, 

 diameter up to 2 mm.; other corallites on the under surface are immersed, or the inner wall 

 may be poorly developed or absent, the outer wall not often as much as 2 mm. long. On 

 the basal expansion the wall away from the growing edge is usually elevated as a lip and 

 considerably thickened. 



On the upper surface the branchlets occur singly or in groups of twos or threes. They 

 are erect in the central area, outside of which they are inclined but curve upward. Height 

 from about 13 to nearly 20 mm.; basal diameter 4 to 6 mm.; apices 4 to 7 mm. apart. 



Axial corallites, average about 1.5 mm. in diameter, exsert up to 1.25 mm., usually 

 less; thickness of walls less than the length of the calicular radius. Primary septa distinct, 

 but a directive only sometimes reaches the axis; secondaries rudimentary or absent. 



Radial corallites spreading; decrease in prominence inferiorly; outer surface costulate. 

 Outer wall: length, about 1.5 mm.; width of tip 1.5 mm.; edge thin and friable. Inner 

 wall usually not developed. Apertures labellate; outer lip in plan usually has a rounded 

 outline; rarely are the apertures somewhat dimidiate. Viewed in profile the plane of the 

 apertural margins slightly ascends from its inner margin outward or is nearly perpendicular 

 to the surface of the branch, but in no instance was it flattened or depressed. The directive 

 septa are usually distinguishable; but the other septa are usually rudimentary, vestiges 

 of secondaries can sometimes be recognized. 



On the central area between the erect branchlets all the corallites are immersed. 



Cuenenchyma rather porous, delicately costulate and spinulose. 



Station, Murray Island: Line I, southeast reef, 800 feet from shore; depth 10 inches; 

 bottom, broken coral. 



Specimen No. 2, plate 7/, fig. 2: 



This is a marginal fragment of corallum which had assumed the horizontal-plate growth- 

 form. Its inner edge is 24 mm. thick. The figure (plate 71, fig. 2) adequately illustrates it. 

 The structural characters are similar to those of specimen No. i. 



Station, Murray Island: Line I, southeast reef, 1,600 feet from shore; depth, 10 inches; 

 bottom hard, rocky. 



Distribution. — Great Barrier Reef and Torres Straits. 



Acropora (Lepidocyathus) spicifera (Dana). 



Plate 68, figures 3, ■ja, jb, specimen from Cocos-Keeling Islands. 



1846. Madrepora spicifera Dana, U. S. Expl. Exped., Zoopli., p. 443, plate 33, figs. 4, 4a, ^b, 5. 

 1893. Madrepura spicifera Brook, Cat. Genus Madrepora, p. 92. 



The following is a description of a specimen collected by Dr. Wood Jones: 



The corallum "consists of low spreading branches; it is 6 to 9 inches in diameter and 

 2 or 3 feet in circumference. The branches extend horizontally, but only in places do they 



