109 



costae are finer, more numerous, and closer thancan be easily expressed 

 on a small sized drawing - . On the whole I should not be disposed to 

 regard the species as distinct ; but the variation is very important, 

 varying in amount in different specimens. It will be seen that aliform 

 appendages are therefore not of such specific importance as they have 

 been thought to be. 



With regard to the genus, I must observe that I do not think the 

 mere deltiforin pali a sufficient generic distinction from Trochocyathus. 

 But all those species which I have classified as Deltocyathus have really 

 no columella. The pali are united to the septa and meet in the middle 

 giving rise to a rather compact tissue in which the component septa are 

 generally distinguishable in this species, but not in D. viold. Most of 

 the species may be said to represent Trochocyathus in Australia. I chink 

 if it be added to Deltocyathus that there is no columella, there will be 

 no necessity for creating a new genus. It must be acknowledged that 

 the divisions as they at present stand are not satisfactory. If it were 

 clearly stated that there is no columella because the visceral cavitv is 

 empty as in Desmophyllum, or that the septa and pali meet in the centre, 

 as in Conocyathus, there would be no ambiguity. At present both are 



described as having no columella. 



The fossil at present preferred to is common in the Murray River 



cliffs, four miles south of Morgan. Dimensions, about the same as D. 



excisus. 



It is remarkable that though D. excisus is very common at Muddy 



Creek, I have never seen a specimen with any form of base except two 



small basal prolongations, though this form is the exception at the Murray 



beds. The deeply lobed septa are rarely seen in the Muddy Creek 



specimens. 



The next species is a Trochocyathus, of which we have already two 



fossils described and two doubtfully from New Zealand. In this genus 



the fossils extend from the present day to the Lias. 



Trochocvathus heterocostatus, n. sp., pi. 2, fig. 1. 



CoraUum short, broadly wedge-shaped, with a very conspicuous 

 oval, slightly couvex, radiately ribbed, basilar scar, which has a neat, 

 somewhat prominent, clearly defined margin ; base proportioned to calice 

 as five to eight. Calice, elliptical, shallow ends of major axis slightly lower 

 than those minor. Costae, distinct, granular, with fine granules, and dis- 

 posed in four cycles, but in a very singular and exceptional manner. 



