318 PROFESSOR P. M. DUXCAN ON THE 



Genus Bathtcyathus, Milne-Edwards & Jules Haime, 1848. 



Bathycyathus atlanticus, Duncan. (Plate XLVIII. figs. 1, 2.) 



The corallum is cii-cular in outline at the base, but becomes compressed above, so 

 that the axes of the calice are very unequal. 



The corallum is in the shape of a reversed and compressed cone. 



The calice is elliptical in outline, and the great axis is on a lower plane than 

 the smaller. 



The septa at the reticular margin are exsert, and project outwards so as to give a 

 very open aspect to the deep calice. The septa are unequal, and the primary and 

 secondary laminae are very prominent. The septa of the last cycle are larger than the 

 penultimate. 



There are four complete cycles of septa, and also three derived septa from the fifth 

 cycle, so that there is an appearance of thirteen sets of three septa and thirteen large 

 septa. The septa are granular, and ornamented -with radiating lines of granules. 



The pali are large, distinct, prominent, very granular, and are placed before the 

 tertiary cycle. 



The columella consists of essential and ribbon-shaped processes, and is well developed 

 and deep in the fossa. 



The costse are broad, granular, and subequal; but those of the largest septa are 

 distinctly prominent far down towards the base. 



Height of corallum 1 inch to 1^ inch ; length of calice xs inch ; breadth of calice 

 Yo inch. 



Some fragmentary specimens evidently belonged to larger forms. The coral was 

 found in No. 17ff and No. 17 dredgings, in the second expedition of the 'Porcupine,' 

 and in 740 and 1095 fathoms. 



The genus Bathycyathus is closely allied to the Caryophyllice ; and were it not for the 

 peculiar structure of the upper part of the septal apparatus, it would be included 

 amongst them. 



The species hitherto described, viz. Bathycyathus chilensis, Ed. & H., B. indicus, 

 Ed. & H., and B. sowerbyi, Ed. & H., have five complete cycles of septa. The first two 

 are recent forms, and are probably identical, and were dredged up off the coast of Chili, 

 at a depth of 80 fathoms, and off Juan Fernandez. 



The fossil species (Bathycyathus sowerbyi, Ed. & H.) of the Upper Greensand is never 

 found in a perfect state, and is closely allied to the recent forms. 



Hence the new species, with its defective fifth cycle, is less closely allied to the 

 Cretaceous type than its Pacific congeners. The genus has not been found represented 

 in any Upper Cretaceous or Tertiary strata. 



