On Calamoporce in gravel deposits near Ann Arbor, Mich. 399 

 Calamopora turbinata Billings, Canad. Journ., 1859, p. 109; lb. 1860, 



This peculiar Calamopora is a very near relative to C. basaltica, 

 and differs from it only in external form, which is either turbi- 

 nate, like a turbinate Cyathophyllum, or it forms large lenticular 

 masses, with coarse rounded folds on the lower side which is 

 generally exposed, while the upper side is almost invariably 

 adhehng to the enclosing rock ; or in other cases, the internal 

 portions of the coral are decomposed, and only the external ends 

 of the tubes, which are strengthened by their massive opercula, 

 are left in the form of excavated horns, or more expanded 

 funnels or dishes. Billings has described the corals so well that 

 any farther remark is superfluous. He calls the appearance of 

 an operculum an epitheco, which word should be restricted to 

 a different sort of an envelope. 



It is rarely found silicified, in association with the other Cor- 

 niferous limestone fossils; it is very common in calcareous frag- 

 ments containing immense numbers of broken Brachiopods, 

 Crinoidal stems, and Bryozoa, belonging to the lower strata of 

 the Helderberg group. 



Calamopora pobjmorpha belongs to more destructible calcareo- 

 argUlaceous strata, and is very poorly preserved in our gravel. 

 The ramose forms known as C. cervicornis, C. reticulata, and C. 

 dubia, with a number of allied forms, are found finely preserved, 

 hut I reserve their description for some future communication, 

 which will also embrace the numerous varieties of Limaria, and 

 the ramose forms of Alveolites. 

 Michelima convexa D'Orbigny ; Billings, Canad. Journ., 1859, p. 112. 



It is not unfrequently found, but rarely well preserved. 



Omitting a general description, I have only to nnention a re- 

 mark of Mr. Billincrs, that Michelinia differs from Favosites by 

 having the verticallamellee represented by vertical striae, while 

 in Favosites series of minute spinules form the equiva ent. But 

 Michelinia convexa and also M.favosoid£a have the inside covered 

 with just as many rows of spinules as they have longitudinal 

 strise, because every interval between two strne bears a row of 

 spinules. On the other hand the strise are also well enough 

 developed in Calamopora, only less numerous than in Michelinia. 

 Michelinia intermittens Billings; Canad. Journ., 1859. 



A coral which corresponds perfectly with the description given 

 by Mr. Billinsrs is not rare here. , j , i . , 



Its tubes are frequently contiguous and connected by lateral 

 pores, which are placed in the intervals between the constnc- 

 tions'; diaphragms vesicular, longitudinal stri^ mdisti net, and 

 spinules irregularly disperedover the interior of the side- walls. 



