CORALS FROM THE PERSIAN GULF. 1029 



side, there are more than the normal number of septa. It 

 appears as if the tertiary septa of both these chambers had been 

 split by a wholly superfluous quaternary septum, while in one 

 case a quaternary septum has been further split by a super- 

 numerary quinary. The same phenomenon is apparent to a 

 greater or lesser degree in all the remaining five specimens. In 

 one specimen there is a sudden outpushing of the wall of the 

 calice between a primary and a tertiary septum, in which there 

 are no fewer than nine instead of the normal thi-ee septa; in 

 every case there is a costa to correspond with each septum, and 

 the alternation of large and small septa and costse is maintained. 



Seven specimens fixed on to a mass of mud, shell and serpulid 

 tubes. 



Locality. From Cable 60 miles S.W. of Bushire, Persian Gulf. 

 Depth 30 fms. 



Two specimens are infested by the Cirriped Pyrgoma stokesii, 

 which forms a bulbous gall within the wall of the coral (PI. 

 LVII. fig. 5 c). This distortion does not, however, interrupt the 

 regularity of the costfe, which are distinctly visible on the outside 

 of the parasitic chamber ; nor does the presence of this parasite 

 appear to affect the number of septa ; there is no excess or 

 shortage of septa in the attacked specimens beyond that which is 

 normally observed in the unattacked individuals. 



Genus Trematotrochus T. Woods [39]. 



Trematotrochus zelandi^. (PI. LYII. fig. 4 ; PI LVIII 

 figs. 15-17). 



Conocyathus zelandice Duncan [14]. 



Corallum I'egularly conico-cylindrical, free, without trace of 

 attachment. No epitheca. Height of largest specimen 7 mm., 

 diameter of calice 3-4 mm. Costaj in four complete cycles, 

 prominent, smooth, and equal in the upper part of the corallum. 

 Only those of the first two cycles extend to the base ; those of 

 the third cycle extend downwards for about three-quarters, and 

 those of the fourth cycle for a distance varying between a third 

 and three-fifths of the height of the whole corallum. The costte 

 between those of the second and third cycles are longer than the 

 costse between those of the first and third cycles ; they do not 

 join those of the preceding cycle, but there is a thickening of the 

 costse of the fii'st three cycles below the point at which that of 

 the succeeding cycle ends. Intercostal furrows penetrated by 

 minvite, regularly disposed perforations (PI. LVII. fig. 4). Calice 

 circular, no fossa. Septa in six systems of three complete cycles, 

 all exsert, those of the first cycle more prominently so than those 

 of the succeeding cycles ; very thin and beset with small spinous 

 granulations. Septa of the third cycle join those of the second 

 a short distance below the lip of the calice ; they are incomplete 

 at their inner margins, large fenestrations occurring at the point 



Proc. Zool. Soc— 1911, Xo. LXX. 70 



