394 On CalamoporcB in gravel deposits near Ann Arbor, Mich. 



hy incrustation. I strongly suspect that by misapprehension 

 of such specimens the genus Dania has been called into existence, 

 and will finally have to be erased from the list of names. 



Ihecorallum is found in tabular undulated fragments, with 

 parallel tubes; or in placentiform expansions, with flattened or 

 conical base, on which sometimes remains of an epitheca are 

 preserved. Ca/amopora Gothlandica from the Eifel differs from 

 It, by the inequality and more rounded nature of its tubes, by 

 Its tuberose or piriform mode of growth, by much coarser and 

 more numerous spinules on the side-walls, by much larger and 

 more numerous lateral pores, which are surrounded by a shal- 

 low excavation, from the upper end of which a large spine gen- 

 erally protrudes. b f & 



Calamopora venusta Ksill—Aetroceriiim venustum Hall, is a very 

 near relative of the two former species. Its tubes are about one 

 millimeter wide, sometimes less. 



Twelve longitudinal rows of spinules are planted on the inner 

 circumference of the tubes, which often grow so long as to reach 

 the centre. The upper face of the diaphragms is also spinulous. 

 The diaphragms are flat, but often also ol" warped aspect, from 

 the presence of lateral depressions. Pores are disposed along the 

 sides in one or two rows. 



In some specimens the tubes are more than one millimeter 



les not so largely developed, but otherwise 



differ much. It occurs in our gravel banks 



.......J .w i..cv^iiicuLs of larger masses, or in placentiform laminate 



cpansions with an epitheca on the lower side. The rock enclos- 

 g the three preceding Calamopon 

 Orummc"-!'- t„i„_j .1 . 



Ihe foTlowing species of Calamopora occur in a siliceo-calca- 

 reous rock, which, judging from the character of its fossils, is 

 Identical with the Corniferous limestone of New York and 

 Canada. 



Calamopora kemispherica Yandell and Shiimard ; Favosites alveolarii 

 Hall, Geo). Report New York, 4 Distr.; Emmonsia hemispherica Milne 

 IS^r ^°'^ ^^^'™^ ' ^"^^^^^^^ hemispherica Billings, Canad. Journ. 



This coral is found in a number of different varieties, which 

 are so intimately connected by intermediate forms that it would 

 De unnatural to undertake a division into several species. Milne 

 lidwards enumerates three species, which are distinguished by 

 IZ'^^ ?i ^^^ ^"^^' ^y '"*^^^ o^ less regularity in the diaphragms, 

 and by the number of pore-rows on a side, all of which charac- 

 l7llnnZZ^^ variable, even in single specimens, and consequent- 

 y cannot be relied on. Specimens with tubes nearly three mU- 



