1026 MISS R. HARRISON AND RROF. S. J. IlICKSON ON 



//. pulchellus Rehberg- [37]. Intermediate between Types B 

 and 0. Generar facias, fifth septal cycle and depressed 

 columella, Type 0. Alternating costfe and distribution of 

 lateral pores, Type B. 



H. oUongatus Rehberg [37]. Type C. 



H. wood-masoni Alcock [1]. Type B. 



The specimen from the Persian Gulf also belongs to Type B. 



The other specimens of Heterocyathus in the Persian Gulf 

 collection constitute a new species. The tendency to remnin 

 conical is very marked; the costee are distinct from those of other 

 species ; and the uniformity in size separate it sufficiently until a 

 good series of intermediates are found which will link it up 

 with II. aUernatus. 



I therefore recognize in the genus the following species : — 



1. II. cequicostatus Wilne-'EAwfwds &. Jliiime. 



Stephanoseris rousseaui Milne-Edwards & Haime. 



H. parasiticus Semper. 



II. philippinensis Semper. 



H. ohlongatus Rehberg. 



H. pulchelhos Rehberg. 



11. icood-'inasoni Alcock. 



2. H. alternatus Yerrill. 



H. cequicostatv,s (Gardiner's Type II). 



3. //. heterocostatibs, sp. n. 



Heterocsathus ^quicostatus Milne-Edwards & Haime [29]. 



A single specimen belonging to Type B. Costfe, equal in 

 number to septa, extend to base, beset with irregular spines. 

 Base roughly granular. Slight calicular fossa. Septa in six 

 systems of four complete cycles, very spiny ; those of the fourth 

 cycle fuse with those of the third, and these in turn fuse with 

 those of the second. Inner margins of septa pass imperceptibly 

 into the trabecular columella. 



Locality. Telegraph Cable, Persian Gulf. Depth 40 fathoms 



Heterocyathus heterocostatus, sp. n. (PI. LVII. fig. 6 ; 

 PI. LYIII. fig. 14.) 



Corallum simple, free, variable in shape from a low discoid 

 form to a conical cornuate form. Upper part of corallum 

 deeper in colour than base. Height varies between 3 mm. and 

 7 mm., and calice between 3-5 x 3 mm. and 6x5 mm. Costfe of 

 two distinct types. Those corresponding to the septa of the first, 

 second and third cycles ai'e visible from the base to the tip of the 

 calice, prominent sharp ridges with a single series of coarse 

 o-ranulations ; the alternate costfe, corresponding to the septa of 

 the fourth cycle, extend only about half-way down the corallite 

 from the lip of the calice ; they are less prominent, and beset 

 with numerous irregular granulations. Calice slightly elliptical, 



