96 



cycle in the half-systems ia which a fifth cycle is developed) 

 being the largest. 



Coluraella deep-seated, consisting of a niultitude of small pinnacles 

 or prismatic grauules arranged in three long rows. 

 Greatest height of corallum 20 millim. 

 Major diameter of calicle 21 » 

 Minor » » » 12 » 



The corallum is of a snow-white colour. 



10. Trochocyathus pileus n. sp. 



This species, which is represented only by a dead and broken 

 specimen, appears to be closely related to Trochocyathus mitratus 

 (Goldfuss) from the Miocene of southern Europe. 



Though its columella is almost lamellar, it has no connection 

 with Placocyathus. 



Corallum shaped somethiug like a Phrygian cap, conical, mo- 

 derately compressed, with the acumiuate base curved in the plane 

 of the minor axis. 



Costae equal, and equally salient from calicle to acuminate base, 

 all very elegantly milled or beaded throughout their extent. 



The calicular orifice appears to have been nearly horizontal, 

 and the fossa not very deep. 



The septa are niuch broken in the unique specimen; their 

 surfaces are strongly echinulate, and they are in six systems of 

 fipe cycles, the fifth cycle being incomplete. Those of the fourth 

 cycle usually unite with those of the third, some distance above 

 the columella. Those of the first two cycles, which are equal, 

 are the largest and far the most exsert; and those of the lower- 

 most cycle are much more exsert than those immediately preceding 

 them, being in fact little less exsert than those of the first two 

 cycles. 



The pali, which are lamelliform aud echiciate, are about 30 in 

 number, aud are placed opposite all the septa except of the last 

 cycle. 



