1870.] DUNCAN—AUSTRALIAN OORALS. 307 
the development of their cost. They have not a close affinity with 
the recent Trochocyathi of New Zealand; and the subhemispherical 
form somewhat resembles the Miocene species of Tortona and 
India. One of the species is probably the “ Petraia” mentioned by 
Mr. Wilkinson. The only living Trochocyathi are found off New 
Zealand. The genus culminated in the Miocene of Europe; and 
species of it were rare in the West-Indian deposits. 
Deltocyathus italicus is a well-marked form, although the genus 
is hardly worthy to be separated from Trochocyathus. The shape 
and ornamentation of the corals are most beautiful; and they form 
the prettiest of all the miocene Madreporaria of Europe. Very lately 
Count Pourtales dredged up many specimens of dead Deltocyathi in 
270 fathoms off Havanna, one of which he sent to me. A careful 
examination of the Miocene, West-Indian, and Australian forms leads 
to the belief that they are not specifically distinct, and that no one 
would consider them other than varieties if the localities whence they 
had been derived were unknown. ‘There is a slight difference in 
shape, but nothing at all specific ; and the costs are more moniliform 
in one and more spiny inanother specimen. As I cannot distinguish 
a specific difference, I have called the Australian form ‘ variety aus- 
tralensis;” and I would suggest that Pourtales’s Deltocyathus Agassiz 
should be known as variety Agassiz: of the species ztalicus. The 
Deltocyathi are small forms and very readily passed over ; but I could 
not find any amongst the collections of fossil West-Indian corals I 
have examined. No species have been found in the great Coral 
ocean. 
The Sphenotrochi of the Australian Cainozoic deposits differ from 
all others in having a curious notch at the base. In one species 
this is so marked as to produce the appearance of two lateral pro- 
cesses on either side of the base. They present, moreover, an ano- 
malous relation between the septa and the coste. The existing 
species of the genus are found around the 8.W. of England and the 
Irish coast ; and the fossil forms are to be distinguished in European 
Kocene and Miocene strata and in the Crag. All these have the 
septa continuous with the costal projections. The Australian species 
have the septa not continuous with the coste, but with the inter- 
costal spaces, so that the costz are on the outside of the interseptal 
spaces. No living species of the genus have been found in the great 
Cora] ocean, or in the West Indies. The alliance between the genera 
Sphenotrochus and Placotrochus is strengthened by the discovery of 
the Australian forms of the former genus. 
Conotrochus is a genus founded upon some well-marked Sicilian 
corals by Seguenza. They were found in the uppermost of the so- 
called Miocene strata or the ‘‘ Marne Giallastre,”’ which are below 
the horizon of Flabellum siciliense, Edw. & H. (lowest beds of Older 
Pliocene). The generic characteristics are those of a Turbinolian 
without pali. The corallum is simple, fixed when young, free when 
old. The columella is fascicular and well- developed. There is a 
strong epitheca. The shape of the corallum is cl: eae turbinate, 
eylindro- conical, straight or curved. 
