1030 MISS R. HARRISON AND PROF. S. J. HICKSON ON 



where the septa of the thivd cycle join those of the second, and 

 those of the first and second join the columella. The lower 

 fifth of the corallum has been filled up internally by a secondary 

 deposit of calcareous matter, but the outline of the original struc- 

 ture is faintly discernible in photographs of sections at this level, 

 and reveals that the columella is parietal, formed by the union of 

 the inner ends of the septa. 



Three specimens. 



Locality. Persian Gulf. Depth not recorded. 



The genus Treinatotrochus was proposed by Tenison Woods [39] 

 for a fossil from the Miocene of Australia. The coral had all 

 the characters and appearance of a Turbinoliid, but with the 

 important difierence that the wall was penetiated by large per- 

 forations between the costse, giving free communication between 

 the interseptal chambers and the exterior. 



This remarkable coral did not receive the attention it deserved, 

 and subsequent authors received sceptically the statement that 

 these perforations wei'e really present ; for the point called in 

 question the validity of the division of the Madreporaria into 

 Perforata and Imperforata. Duncan [15] pointed out the diffi- 

 culty of placing this genus, but referred it to the Turbinoliidfe 

 in close relation with Tv.rhinoUa, Stylocyathus, Conocyathxis, and 

 Bistylia *. 



In a series of papers published in the Transactions of the 

 Royal Society of South Australia, Dennant [7 &l 8] has since 

 described six more fossil forms and one recent form {T. rerconis) 

 from Australia and Australian Seas. In the first of these 

 papers he describes two species from Eocene a.nd one species 

 fi'om Miocene deposits. The recent species was found in St. 

 Vincent's Gulf and Backstairs Passage at depths of from 15 to 

 22 fathoms. All have the characteristic perforations, which 

 fact caused him to remove the genus altogether from the Turbi- 

 noliidfe and place it among the Eupsammiidee. Later he described 

 three different species from older Eocene beds than those in 

 which his pi-evious species were found, and in two of these 

 the perforations do not pierce the wall, but are merely pore- 

 like cavities extending half-way through the thickness of 

 the wall like the intercostal dimples of some Turbinoliid^. 

 This made him put the genus back among the Turbinoliidse, 

 and he referred to Gregory's [23] suggestion that the Perforate 

 type of coral has been derived from the Imperforate. He 

 further remarked on the wide distribution through time of the 

 oi-iginal species T. fenestratus, and appended a drawing of a 

 portion of the wall cf one of them, placing the existence of the 

 pores beyond all suspicion of doubt. All the previously described 

 species come from Australia, and Dennant pointed out the 



* Duncan uses the plirase "one of the species" as if more than one species were 

 known. At the time of the publication of his paper (1885) I am not aware that 

 any other species had been described. 



