CORALS FROM MURRAY, COCOS-KEELING, AND FANNING ISLANDS. 153 



The similarity in its septal arrangement to Pontes is interesting, and sug- 

 gests, as had previously been maintained by Duerden, 1 the close kinship of the 

 Poritidae and Acroporidae. However, as the foregoing description shows, the genus 

 is clearly Montipora. 



Papillate Montipora. 



Montipora venosa (Ehrenberg). 



Plate 63, figure 3, specimen from Murray Island. Also plate 19, figure 46, of Dr. Mayer's article. 



1897. Montipora venosa Bernard, Cat. Montipora, p. 69, plate 32, fig. 15 (synonymy). 

 1907. Montipora venosa Bedot, Madreporaires d'Amboine, p. 274, plate, 46, figs. 260-262; plate, 47, 

 figs. 263-266. 



The following is a description of specimens of Montipora venosa from Murray 

 Island: 



Corallum forms thickish, undulating or rugose plates which are as much as 3 cm. or 

 somewhat more thick 10 cm. from the edge; obtuse or rounded on the edge, 3 to 13 mm. thick. 

 Upper surface caliculate all over; lower caliculate up to 4 cm. from the edge. No well- 

 developed epitheca, in places a few epithecal threads. 



Calices on upper surface from 1 to 1.25 mm. in diameter, therefore rather large and 

 open; distance apart from 0.5 mm. to 2 mm., crowded where there are no papillae, distant 

 where papillae are present. Margins depressed, walls distinct or scarcely distinguishable 

 from the coenenchymal reticulum. In places no distinction can be made between the two 

 surfaces; in others, the calices of the under surface are smaller, 0.75 mm. in diameter, and 

 are separated from I to 2 mm. by flat coenenchymal surfaces. 



Septa in two complete cycles, primaries long, frequently all 6 fuse in the axis and form 

 a false columella; plane of symmetry distinct. Secondaries smaller, usually but not always 

 well developed; occasionally one fuses to the side of a primary near the axis. 



Ccenenchyma loose-textured; edges translucent; the downward-bending threads may 

 be almost suppressed, or the threads may be symmetrically arranged with reference to a 

 plane of divergence. Over considerable areas the surface may be foveolate; over other 

 areas papillae are irregularly developed, they may fill an interspace between calices, or may 

 be elongate from one to 4 calicular spaces, length of ridges of latter kind up to 9 mm., height 

 up to 2°mm. Little spines project from the angles and points of fusion of many of coenen- 

 chymal threads. 



Stations, Murray Island. — Southeast reef, line I: 



1,400 feet from shore; water 14 inches deep; bottom hard, rocky. 



1,640 feet from shore; water 15 inches deep at lowest tide; hard, rocky bottom. 



Lithothamnion ridge, 1,720 to 1,775 feet from shore. 



The foregoing description is based on 2 specimens 1,400 feet from shore. 



In the specimen 1,640 feet from shore, the texture is more compact; over the 

 humpy part of the corallum the calices are crowded, separated by thin walls, but 

 papillae, slender and erect or rather thick with densely spinulose surfaces, are devel- 

 oped between the calices. 



The specimen from the Lithothamnion ridge is simply foveolate, without 

 papilla;. The texture of its ccenenchyma is more regular and somewhat closer, 

 and the second cycle of septa is more uniformly well developed. 



The specimens from these three stations might be referred to as many species, 

 but the general growth-habit is the same, as also are the calicular and septal char- 

 acters and the arrangement of the coenenchymal threads. The variations consist 

 in relative compactness and regularity of the structure of the ccenenchyma, the 

 crowding of the calices, and the development of the papillae. 



The species belongs in the subgroup of Papillate Montipora designated by 

 Bernard "Papilbe irregular" and satisfies the requirements of Montipora venosa 

 (Ehrenberg). In its calicular characters, by possessing 6 well-developed primary 



'Mem. Nat. Acad. Sci., vol. 8, pp. 542 et sea., 1903. 



