CORALS FROM MURRAY, COCOS-KEELING, AND FANNING ISLANDS. 131 



Dr. Mayer collected a single specimen of this well-known species. Its length 

 is 20 cm.; width 5.8 to 8 cm.; height 7.8 cm. Longitudinal axis of corallum arcu- 

 ate; upper surface arched; lower surface concave; ends wider than the median 

 portion. Vertical distance between calicinal centers up to 8 mm.; horizontal 

 distance usually less, 4 to 6 mm. Parts of the upper surface damaged. 



Station, Murray Island. — Southeast reef, line I, 1,400 feet from shore; water 

 about 15 inches deep at lowest tides. 



Distribution. — Singapore (Gardiner); Philippines (U. S.Nat. Mus.); Amboina 

 (Quelch, Bedot); New Holland and Vanikoro (Quoy and Gaimard). Apparently 

 confined to the western Pacific and eastern Indian Oceans. 



Family AGARICIIDyE Verrill. 

 Genus PACHYSERIS Milne Edwards and Haime. 

 1849. Pachyseris Milne Edwards and Haime, Acad. Sci., Comptes rend., vol. 29, p. 72. 



Type species: Agaricia rugosa Lamarck. 



Besides a good suite of P. rugosa from the southern Philippines, there are in 

 the U. S. National Museum Dana's types of P. speciosa and P. levicollis, and Verrill's 

 type of P. monticulosa ( = P. valenciennesi M. Edw. and H.). The columella is false, 

 formed by axial expansions of the inner ends of the septa, which may produce a 

 more or less lamellate columella or the axis of the valley may be solidly filled. 

 Synapticulae are well developed. 



Pachyseris speciosa (Dana). 



Plate 54, figures 3, 3a, Dana's type of Agaricia speciosa; figures 4, 4a, specimen from Murray Island. 



1846. Agaricia speciosa Dana, U. S. Expl. Exped., Zooph., p. 337, plate 21, fig. 7. 

 1857. Pachyseris speciosa Milne Edwards and Haime, Hist. nat. Corall., p 86. 



Identification based on Dana's type, No. 199, U. S. National Museum. 

 A single young specimen, of which the following is a description, was obtained 

 by Dr. Mayer: 



Corallum 28 mm. tall, attached hy an expanding base, 35 mm. long by 25 mm. wide; 

 ahove it, a peduncle, 25 by 22 mm. in diameter and 6 to 7 mm. high. From the top of the 

 peduncle a thin, infundihuliform lamina extends on all sides, margins subcircular, diameter 

 about 70 mm. Thickness from a knife-edge to I mm. in valleys, and 1.5 to 5 mm., or some- 

 what more, on the collines. Lower surface naked, no corallites and no epitheca; very finely 

 costate; costae near the margin either alternate in prominence or arranged in three sizes, 

 but all are small, 18 to 5 mm.; of these 9 larger and 9 smaller; sides and edges microscopically 

 granulate. Common wall imperforate. 



Width of valleys 2.5 to 3 mm.; height of collines 0.5 to 3 mm.; taller near the center, 

 concentrically arranged, very few monticules, summits rounded; no recognizable calicinal 

 centers. Oral axes at the distal bases of the collines. 



Septa correspond to the costae, imperforate, equal in prominence and thickness, directly 

 continuous across collines, edges microscopically dentate. Granulations crowded; just below 

 septal edges form wings which may fuse from one septum to the next, forming a platform. 

 Synapticulae present. 



Processes from inner ends of the septa fuse along the valley axes and form an almost 

 continuous flat floor. 



Station, Murray Island. — Off the northwest reef, depth 15 fathoms; rocky 

 bottom. 



This specimen is absolutely typical P. speciosa (Dana) except that in its shape 

 the type is a reniform lamina. Besides this species, the U. S. National Museum 

 contains Dana's type of P. levicollis, No. 190, and his Agaricia rugosa is represented 

 by two specimens, Nos. 217 and 218, one of which, No. 218, is his figured specimen. 



