12 LEPTOCYATHUS. 



the secondaries about the middle of the radius. There are indis- 

 tinct traces of pali. 



1 have satisfied myself thai the former determination of this coral 

 was wrong ; it is probably a free Paracyathus, not very unlike P. 

 caryophyllus M.-Edw. and H. 



Height 3 mm., diameter of calicle 2 mm. 



Off the Samboes, in 237 fathoms. 



LEPTOCYATHUS M.-Edw. & H 



Leptocyathus Stimpsonii Pouur. 



Plate III, figs. 1, 2, and 3. 



Corallum free, more or less hemispherical, without mark of ad- 

 herence. Costa? equal, continuous with the septa, without definite 

 boundary, finely serrate and spinous, deeply separated by very 

 narrow furrows, so that the wall proper is invisible. The primary 

 costa? reach nearly to the centre, those of the fourth order embrace 

 and unite with those of the third, and 'the resultant costae of two half- 

 systems unite below the secondaries. This arrangement is seldom 

 regular except in the young, as the base of most of the old ones has 

 the appearance of having been broken and mended, thus introducing 

 much confusion in the arrangement. Calicle circular ; fossa small 

 and not deep. Septa subequal, finely denticulate, the teeth becoming 

 larger towards the interior, crowded, in six systems and four cycles; 

 the arrangement of the different orders as in the costns. Pali in front 

 of the secondary septa very distinct, those of the other orders scarcely 

 distinguishable from the columellar processes, of which there are from 

 six to twelve, crowded and irregularly prismatic. 



The young are almost spherical, the calicle being quite small ; they 

 resemble a Melocactus deprived of its spines. 



The polyp is of a delicate pink or sometimes greenish color, with 

 simple conical tentacles. 



Diameter G to 7 mm. ; height about 3 mm. 



Abundant in GO fathoms off Conch Reef; one specimen in 1GU fath- 

 oms off Tennessee Reef. 



This coral is referred to the genus Leptocyathus with some doubt, as 

 its denticulate septa would really remove it altogether from the family 

 of Turbinolidae. 



