CORALS FROM THE PERSIAN GULF. 



1021 



Costse faintly indicated throughout entire height of the corallum 

 which is also marked with fine wavy transverse accretion lines. 

 Septa in six systems of six cycles of which the sixth cycle is 

 incomplete, while there are present a few rudimentary septa of 

 a seventh cycle. Those of the first three cycles equal and reaching 

 the columella, edges vertical, entire until within about 4 mm. of 

 the columella where a few coarse denticulations may be present ; 

 beset with minvite blunt spines arranged in transverse and radial 

 rows. Septa of lower cycles become successively smaller. Columella 

 parietal, only slightly developed. 



Locality. Telegraph Cable, Persian Gulf. Depth not recorded. 



In the larger specimen there are 175 septa arranged as 

 follows *: — 



This coral differs from v. Marenzeller's species in its smaller size 

 and the presence of numerous rootlets. Gardiner [19] has shown 

 that the presence or absence of such rootlets is a variable 

 character, and he has described rootlets in Flahellum ruhrum, a 

 species in which they had not previously been recognized. 



V. Marenzeller's species was made for a single specimen, and as 

 the agreement between the calicular and septal characters of the 

 specimens under considera,tion and those of the type are so 

 similar, it has been considered advisable not to separate them. 



Family Turbinoliid^. 

 Genus Heterocyathus. 



The genus Heterocyathus has been critically examined by 

 Gardiner [20], who had at his disposal a very large number 

 of specimens. He absorbed the species of Semper and Rehberg 

 in a single variable species originally described by Milne- 



* The septa are considered as being divided into six chambers, bounded by 

 primary septa ; the chambers are considered in rotation beginning with one to the 

 right-hand side of a directive septum. 



