DELTOCYATHUS. 15 



the primary or secondary ones. Columella probably papillose (nearly 

 destroyed in the specimen). 



Diameter 16 mm. ; height, including central knob, 10 mm. 



One dead and badly preserved specimen was brought up by the 

 lead some years ago, by one of the United States Coast Survey 

 parties, from 460 fothoms, in lat. 30° 41' N. and long. 77° 3' W. 



This specimen was described as a Platytrochus by a mere inadver- 

 tence on my part. I place it now among the Trochocyathi with a 

 doubt, since the specimen has lost its columella and pali, if it had any. 

 Its general appearance would place it near T. armcdits M.-Edw. & H., 

 differing from it in having only knobs instead of spines, and equally on 

 the primary and secondary septa. 



DELTOCYATHUS M.-Edw. & H. 

 Deltocyathus Agassizii Pouut. 



DeUocynthus Affasxhii Poukt. Bull. Mus. Comp. Zotil., No. G. 



Plate II., figs. 1 to 5 ; and Plate V., figs. 9 and 10. 



Corallum discoidal, free at all ages. Wall nearly horizontal, or flat 

 conical, sometimes with a nipple-shaped projection in the centre. 

 CostfB well marked, covered with sphiy or smooth granules, generally 

 subequal, but sometimes the primary costse much larger and pro- 

 longed beyond the edge, forming a star. Septa in six complete 

 systems and four cycles, covered with small spinous tubercles. Pali 

 of the first, second, and third cycles projecting generally higher than 

 the septa to which they are soldered at the base. The pali of the first 

 cycle short, those of the third joined to those of the second, but the 

 point of junction not being exsert, the V, or delta, is not as apparent 

 as in the fossil species. Columella papillose and small, rising from the 

 primaiy and secondary pali which meet in the centre. (The colu- 

 mella is represented a little too large in fig. 1, and particularly fig. 2, 

 of Plate II.) 



This coral has been pronounced by Dr. Duncan identical with the 

 fossil species D. italicus. They are certainly very closely allied ; but 

 as far as I have been able to compare them, they are readily distin- 

 guished by the costce, which in D. italicus are formed of large grains, 

 and have thus a moniliform ajjpearance, whilst all the Cuban and 

 Florida!! specimens, although in other respects very variable, have 



