NO. 1526. CORALS FROM FRP.NCH SOMALILAKD— VA VGIIAN. 251 



apart; they arch iij)ward and may reach, or very nearly reach the 

 highest points of the septa. The collines composed of dissepiments 

 and the outer ends of the septa; there is no wall lamella. 



Columella poorly developed, consisting* of a few septal processes, or 

 absent. 



Type. — Museum d'Histoire Naturelle, Paris. 



Paratype. — United States National Museum. 



Remarl's. — This species differs from the other three species of the 

 genus by the absence of a wall ridge or lamella, and by having more 

 numerous septa. 



PHYSOGYRA GRAVIERI, new species. 

 Plate XVIII, figs. ], 2. 



Corallum very vesicular and light; subdiscoid in shape, with a 

 thin, slightly reflexed edge. Greater diameter, 141 mm. ; lesser, 125 

 mm. ; height, 57 mm. The lower surface is almost, but not entirel}', 

 without epitheca; the edge zone evidently extended a considerable 

 distance beneath the peripher}', but there are some serpula tubes and 

 molluscan shells attached to the base. The basal wall is largely dis- 

 sepimental in origin, but apparenth^ not entirely of that nature. 

 Prominent, thin costa? correspond to most of the septa. 



Upper surface gradually rounded. Collins summits indicated by 

 an imperfect, discontinuous, perforate wall; the distal ends of the 

 septa elevated at a sharp angle. 



Valle3^s more or less radiate in arrangement, rather straight or 

 sinuous, they may be long, as much as 111> mm. in length; distance 

 between colline summits, from 11 to 18.5 mm.; depth about 6 mm., but 

 as the wall and the elevated distal ends of the septa form a ridge from 

 2 to 3.5 mm. tall, the valleys are reall}^ decidedly shallow. Calicinal 

 centers distinct, average about 1 cm. apart. 



Septa thin, distant, 5 to 7 large ones to the centimeter, with occa- 

 sional intervening rudimentaries. The larger continue to the summits 

 of the collines and, as has been stated, have their outer ends suddenly 

 elevated and joined one to another by an imperfectly developed wall. 

 The septal margins are microscopically dentate and form somewhat 

 sinuous lines from points slightly above the base of the wall ridge to 

 irregularly developed, somewhat ragged paliform lobes that surround 

 the calicular axis. The inner edges of the lobes are steep, and sur- 

 round the rather shallow calicinal centers. 



Dissepimental endotheca very highly developed, forming vesicular 

 collines that extend across from the bottom of one valley to that of 

 the next, and arch upward to within 2 to 3.5 mm. of the wall summit. 

 Dissepiments thin, arched, from 1 to 3 mm. apart. 



Columella poorly developed, false, consisting of a few spinose proc- 

 esses from the inner ends of the. septa. 



