14 BRITISH FOSSIL CORALS 
Orvper—ZOANTHARIA APOROSA. 
Famity—OCULINID. 
Genus—Diptasus, Lonsdale. 
This genus was established by Lonsdale in Dixon’s ‘Geol. of Sussex,’ 1850, pp. 248— 
254, pl. xviii, figs. 14—28), and was described by the learned zoophytologist with all that 
critical acumen which characterises him. MM. Milne-Edwards and Jules Haime, whilst 
they acknowledge the genus to be “voisin des Synhelia” (‘ Hist. Nat. des Corall.,’ pl. 2; 
p- 115), do not give it a place in their classification. I have, therefore, carefully studied 
and drawn the specimens from the Dixon Collection in the British Museum, and have 
great pleasure in doing justice to Mr. Lonsdale by inserting his genus with slight altera- 
tions, to meet the terminology of the day. 
Genus—Dreuasus, Lonsdale (amended). 
The corallum is encrusting, and very irregular in shape. 
The calices are wide apart, and projecting. 
The intercalicular tissue is costulate. 
The septa are unequal. 
There are no pali. 
The columella is formed by the junction of the larger septa, and does not exist as a 
separate structure. 
Gemmation marginal and intercalicinal. 
The genus is clearly not closely allied to Synhelia, for it has no palular or true 
columellary structures. It approaches the genus Astrohelia, which is a transition genus, 
bringing the Oculinide in relation with the <Astreine through the Cladangie (Milne- 
Edwards and Jules Haime, ‘ Hist. Nat. des Corall.,’ vol. 1, p. 111). 
1. Distasus Gravensis, Lonsdale. PI. I, figs. 1—11. 
The corallum is very irregular in shape and size. 
The calices project, and are irregular in their projection and size. 
The coste are granular, equal, subequal, and unequal in different parts of the same 
corallum. 
There are three cycles of septa, and sometimes some of the fourth cycle are seen. 
