POLYPS AND CORALS. 45 



PAVONIA COMPLANATA Verrill, nov. 



The single specimen of this species consists of a broad 

 plate a quarter of an inch thick, attached at one side, with 

 cells on both surfaces. From the upper side arise in oblique 

 and irregular positions several broad, rounded plates, with 

 sharp edges and nearly even surfaces, without carinations or 

 crests. The plates are two or three inches broad, thick 

 below, often curved and somewhat coalescent. Cells mod- 

 erately large, deep, not crowded, from .1 to .2 of an inch 

 distant. Principal septa about twelve, evenly rounded, 

 thickened within the cells, narrow and thin between them, 

 appearing distant, owing to the delicacy of the smaller sep- 

 ta which alternate with them. Columella a small, solid 

 tubercle. 



Color deep yellowish brown. 



Loo Choo Islands. Dr. Win. Stimpson. 



Resembles P. loculata* most, but besides its different 

 mode of growth, it has much more open and less crowded 

 cells, with larger columella and narrower septa, which are 

 much thinner, more unequal, and less conspicuous between 

 the cells. The texture of the coral is also more dense. 



PACHYSERIS MONTICULOSA Verrill. 



Agaricia rugosa Dana (non Lamarck). 



This species is about .7 of an inch thick below, and about 

 .4 in the middle. The ridges are very irregular in width and 

 height, rising at irregular intervals into conical and oval prom- 

 inences, often .25 of an inch or more high. The ridges are 

 invariably rounded and obtuse, even where they rise into 

 crests, differing widely in this respect from those of P. ru- 

 gosa, which M. Edwards describes as acute. The septo-cos- 

 tal plates are alternately unequal, slightly crispate at the 

 middle of the ridges, strongly granulated on the sides. The 

 striae of the lower surface are prominent, moderately close, 

 scabrous. 



*The gemis Pavonia was established by Lamarck in 1801, and conse- 

 quently precedes its use in Entomology in 1816, on account of which Ed- 

 wards and Haime rejected it. 



