FAMILIES AITD GENERA OP THE MABEEPOEAEIA. 163 



13 well shown; it is imperforate. Before Thamnastrcea was 

 shown to have synapticula, the distinction of the two genera 

 was evident, and Comoseris was the solitary example of a fossil 

 Pungid with confluent calices and an epitheca. It is nowcloselj 

 allied to the endothecate Thamnastrceae, the sole distinction being 

 the presence of collines in Comoseris. 



In introducing several new species of Oroseris to the Oolitic 

 coral-fauna of England, Mr. E. Tomes, F.Gr.S., asserts (Quart. 

 Journ. Gi-eol. Soc. vol. xxxviii. p. 440) that the genus really bears 

 but a faint resemblance to the genus Comoseris. He seems to 

 have misunderstood the diagnoses of the genera, for it must 

 appear on reading them tbat Oroseris can hardly stand as a genus 

 distinct from Comoseris. The only distinction is the length of 

 the ridges bounding the calicinal valleys. 



In many parts of the corals of both genera, there are no ridges 

 for a certain space, every calice not being thus separated, so that 

 such areas dismembered would resemble species of Thamnastrcea. 

 It is this fact which brings the forms so closely together. The 

 presence of the ridges or collines, so continuous in the species, 

 cannot be put on one side in classification, and especially in the 

 face of tlie allied genera Mceandroseris and Plesioseris. 



In placing Oroseris as a subgenus of Comoseris it must be 

 admitted that the first-named form has a more varied shape 

 than was given to it by Milne-Edwards and Jules Haime. Mr. 

 Tomes has delineated an incrusting form and a serai-massive, 

 irregular one, and also a species massive and with a lobed outline. 

 He has shown also that the epitheca may be strong and wrinkled, 

 indeed as much so as in Comoseris. 



Subgenus Oeoseeis, (genus) Milne- Edwards ^ Jules Haime, 

 Fol. Foss. des terr. Fal. p. 130 (1S51). 



Colony in rather thin laminae, and the basal wall is either 

 naked or covered with a rudimentary, or strong and wrinkled 

 epitheca. The calices are subconfluent and separated irregularly 

 by transverse subcristiform eminences (collines), which usually, 

 but not invariably, limit simple series of calices and do not extend 

 the length of the colony. The columella is rudimentary. 



Distribution. — Fossil. Jurassic : England, Europe. J^eo- 

 comian ? : Europe. Cretaceous : England. Eocene : Europe. 

 Miocene of Italy. 



11* 



