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



By disease, parts of some specimens of this coral have become 

 so transformed that they would not be suspected to be Calamop- 

 orae, if they were not connected with tubes of regular form. 

 Casts of such specimens are represented by a network, composed 

 of geniculate, nodose, vertical columns, which are connected by 

 numerous horizontal side branches, equally thick with the col- 

 umns. The walls of the tube and its lamellae are thickened enor- 

 mously at the expense of the openings, while at the same time, 

 the side-pores enlarged, and assumed the form of connecting 

 tubes. A similar disease is noticed in some ramose specimens 

 of Calamopora, from the Eifel, which appear like solid branches, 

 perfectly, penetrated by tortuous worm holes. 



The external form of this coral is indicated by its name. 

 Earely remainders of an epitheca can be noticed, which seemed 

 to be restricted to a small root portion. 

 Calamopora epider 



Billings confounds this coral with specimens of the Niagara 

 group as well as with Eifel specimens, but with neither of them 

 has it much similarity. By having lamellose projections on the 

 side- walls instead of spinules, it differs from both, and shows its 

 close affinity to Calamopora hemispherica, from which it differs, 

 by a different mode of growth, by larger tubes, by regular sim- 

 ple diaphragms, and by smaller less numerous side-pores ; but 

 because C. hemispherica sometimes has also its diaphragms more 

 regular, and does not differ very much in the size of its tubes, it 

 ' diflacult to determine, in fragments, f- 



expansions, with a conical basal portion ; from the surface oi 

 these expansions, new expansions sprout up in terrace-form. 

 The whole underside of the mother expansion, as well as ot 

 the terraces, is covered with a concentrically wrinkled epitbeca. 

 The tubes which have in C. hemispherica an inclination to form 

 an arch directed outwards, are in this species more bent up- 

 wards, which is the cause of its having a flattened placentiform 

 surface. 



It is already mentioned, that lamelliform horizontal projections 

 entirely similar to those of C. hemispherica are placed on t&e 

 inside of the tube-walls, but these remain in the form of Imgui- 

 form squamee, and do not often help to form the diaphragms, 

 which are perfectly regular, flat, or warped by the development 

 of some lateral depressions. These depressions are in this spe- 

 cies never so numerous and so regular as to give the end ceils a 

 star-like aspect. 



Distance of diaphragms not large, usually three or four m the 

 space of a tube-diameter, which varies from two to three miin- 



