CORALS FROM MURRAY, COCOS-KEELING, AND FANNING ISLANDS. 139 



Habitat and color, Cocos-Keeling Islands. — Dr. Wood Jones says: 



"Colony from Pulu Tikus barrier, western end. This is not at all a common coral in 

 the atoll, and I found it in only one situation, i. e., on the underside of the overhanging 

 margins of deep barrier pools. It grows as an incrusting layer and rounds off the jagged 

 edges of these pools. The color while alive varies from greenish brown to reddish brown; 

 after death it turns green." 



Distribution. — Red Sea (Brueggemann, Klunzinger); Maldives, Minikoi (Gar- 

 diner); Cocos-Keeling (Wood Jones); Funafuti and Rotuma (Gardiner); Fanning 

 Island (Carl Elschner); Hawaiian Islands. In the Maldives it ranges in depth 

 from low tide to 40 fathoms; range in depth in the Hawaiian Islands from surface 

 to between 26 and 29 fathoms. 



Genus CCELOSERIS, new genus. 

 Type species: Cceloseris mayeri Vaughan, new sp. 



Apparent generic characters: Corallum of massive growth-form. Calices polygonal, 

 separated by simple, imperforate walls, which are secondarily thickened by vesicular endo- 

 thecal dissepiments. Asexual reproduction by subequal fission. Septa imperforate, margins 

 subentire, microscopically dentate. Synapticul.TP present, but rare; when present they are 

 near the wall. No columella. 



This species is separable from the massive species of Pavona by the fewness of 

 its synapticulae and the absence of a columella. 



Cceloseris mayeri, new genus and species. 



Plate 58, figures I, la, li, 2, 30, ji, specimens from Murray Island. Also plate 14, figure 18, of Dr. Mayer's article. 



The following is a description of Cceloseris mayeri: 



Corallum forms rounded, flattish, or columnar masses, up to 11 cm. in diameter by 10 

 cm. tall, and perhaps much larger. 



Corallites polygonal, separated by smiple, continuous, imperforate walls, which are 

 secondarily thickened by steeply sloping dissepiments. 



Calices from 4 mm. to 6 mm. in diameter, an occasional dividing calice 7 mm. long. 

 Septa directly continuous between adjacent calices; in a small calice, about 22 distinct, 

 8 larger and longer, a few scarcely perceptible rudimentaries; in a large calice, 5.5 mm. in 

 diameter, the number is 33, 10 larger than the others, I to 6 smaller septa between 

 each pair of larger; arrangement therefore irregular. Upper septal edges slightly exsert, 

 finely dentate, flattened or arched above; mner edges fall steeply into the narrow open axial 

 cavity. Septal laminae solid; faces with very minute granulations. 



Two zones of dissepiments; those in the outer zone steeply inclined next the wall; those 

 of the inner zone more nearly horizontal; the two zones separated by a vertical wall within 

 the corallite wall proper. Distance between the dissepiments 0.5 to 0.75 mm. Synapticui;e 

 rare, occasional near the wall. 



There is no columella. 



Asexual reproduction by suhequal division. 



In a thin section (see plate jjg, figs. 3, 30), the large septa continue from one calice to 

 the next, but with a distinct euthecal line between their peripheral ends. The ends of the 

 small septa abut against the eutheca and are not continuous across the wall; however, with 

 increasing size the small septa overgrow the eutheca and then are confluent between calices. 



The septal trabeculae are from 0.05 to o.io mm. wide, /. e., there would be from 10 to 

 20 teeth to I mm. on the septal edges. The growth segments of the septa are from about 

 0.6 to about I mm. wide. 



Dissepiments are abundant; synapticulae rare, occasional near the wall, but they are 

 distinctly present and closely resemble those in Agaricia agaricites. The general resemblance 

 to the microscopic characters of the last-mentioned species is striking. 



