I96 PAPERS FROM THE DEPARTMENT OF MARINE BIOLOGY. 



Distribution— -Torres Strait; also at Nasugbu, Luzon, Philippine Islands, Alba- 

 tross, 1908. The intermediate septal denticles of the latter specimens average 

 taller than in those from Murray Island. 



6. Porites mayeri, new species. 

 Plate 86, figures I, la, lb, specimen from Murray Island. Also plate 13, figures 9, to, 1 1, of Dr. Mayer's article. 

 1905. Porites queenslandia secunda ct trUcsima Bernard, Cat. Porites Indo-Pacific, p. 136, plate 17, fig- 8; 

 plate 21, fig. 23. 



The following is a description of this species: 



The corallum has an incrusting base, above which it rises into a mass with gibbosities 

 and irregular lobes and ridges, but does not form plates. '1 he lower edges frequently show 

 successive incrustations, one above another. Occasionally a colony may be rather regularly 

 rounded, i. c, without the gibbosities. , • , , x , T , ,„ 



Calices conspicuous, excavated, polygonal or subcircular; large, diameter 1.5 to 

 2 mm., an intermediate size the more usual, except in the bottoms of depressions, where 



it mav be 1 mm. or less. . 111 



Walls present two aspects: (1) On the sides, nearthe tops of lobes, the mural trabecular 

 mav be distinct, but even here they are compressed in planes transverse to the walls; they 

 are joined by concentric bars; (2) the mural trabecular are scarcely distinguishable in a 

 reticulum composed of projecting, interrupted, plate-like, radial structures joined together 

 by concentrically arranged synapticulae. The top of the reticulum may be Hat. 



Septa 12, 4 lateral pairs, solitary directive, members of the triplet separate from one 

 another Outer zone of synapticulae well developed, with a ring of prominent, rough, 

 irregularly shaped denticles rising above it. Outside this synapticular zone the septal 

 ends are usually bifurcate, sometimes trifurcate, and are_ continued into the radial struc- 

 tures which extend to or even across the wall and combined with it build the reticulum 

 already noted. Usually the palar formula is complete, the pah on the solitary directive 

 and the members of the triplet being well developed; but those before the lateral pairs 

 average taller, somewhat thicker, and reach nearly to the level of the wall. 1 he palar 

 ring of synapticulae is irregularly developed, usually incomplete. Often there is between a 

 nakis and the outer synapticular ring a well-developed denticle, which appears to represent 

 the emergent end of a trabecula. The septa are composed of inwardly inclined trabecular, 

 which in places result in a denticle intermediate between the synapticular rings. Septal 

 faces rough, but the interseptal loculi are rather open, the openness being increased by the 

 incompleteness of the palar synapticular ring. . 



A weak columellar tubercle persistently present. It is usually compressed in the 

 plane of symmetry and attached to one or the other or both directive septa. Lolumellar 

 tangle variable in development, lax or fairly compact. 



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



600 feet from shore; water 15 inches deep; sandy bottom. 



650 feet from shore; water 18 inches deep; rocky bottom. 



675 to 720 feet from shore; water 12 inches deep. 



800 feet from shore (type); water 11 inches deep; bottom hard, rocky. 

 1,000 feet from shore; water 17 inches deep; bottom rocky. 

 1,200 feet from shore; water 9 inches deep; bottom rocky. 

 1,220 feet from shore; water 14 inches deep; sandy bottom. 

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

 1,600 feet from shore; water 10 inches deep; bottom hard, rocky. 



As Bernard has pointed out, his Porites Great Barrier Reef (42)39 is probably 

 the same as this species, but as I am not positive it is omitted from the synonymy. 



There are 13 specimens of this species, furnishing a fairly satisfactory suite. 

 Except in form almost the extremes of variation are shown in the two specimens 

 from 800 feet from shore; one of these is the type (see plate 86, figs. 1, la, lb), on 

 which the detailed description is based; the other is the variant. The nature of 

 the variation, as has been indicated, consists in the degree of the development of 

 the intercalicular reticulum. The variant referred to usually has a distinct elevated 



