390 On CalamoporcE in gravel deposits near Ann Arbor, Mich. 



The following pages will be a description of these remains, and 

 I hope that my observations, although concerning objects which 

 are generally well known, will add something to our knowledge. 



Calamopora is defined by Goldfass as a corallum composed of 

 tubes, which are connected by lateral perforations in the walls, 

 and divided into compartments by transverse diaphragms. 



"Within these limits he included the genus Chaetetes or Sten- 

 opora, supposing its walls to be perforated, but it is now suffi- 

 ciently ascertained that the coral described by him as Calamopora 

 Jibrosa has no lateral communication between its tubes. 



Milne Edwards, in his Monograph of British Devonian corals, 

 describes and delineates a Favosite-^ jihrosm, with lateral pores, 

 and identifies his specimens with Goldfuss's figs. 3a and 6, Tab. 28, 

 but the correctness of this observation is very doubtful; at all 

 events, the specimens from the Eifel, and those which Goldfuss 

 had from Lexington, Kentuckj^ do not exhibit such perforation. 



The distinction made between Chaetetes and Stenopora brings 

 all the American forms, and those from the Eifel, to the latter 

 genus, leaving for Chaetetes only theEussian specimens, which I 

 have never had an opportunity of seeing. 



Besides the exclusion of those forms to which the established 

 generic character of Calamopora would not apply, a number of 

 subgenera have been created from the remaining material. 



Alveolites comprises Calamoporge with depressed tubes and 

 similar cell-mouths opening obliquely to the surface, and form- 

 ing a projecting lip with the exterior half The connecting pores 

 are proportionally larger and more irregular than in ordinary 

 Calamoporae, and also the diaphragms are less regular. I^s ^""^^ 

 are frequently flexuous, with the side- walls intimately united, and 

 part of the younger tubes appear to be side branches of the older 

 tubes, but simple side-walls and an increase by division of the 

 older tubes are never observed, the walls having always in the 

 centre a distinct line of demarcation. . •, 



Alveolites forms generally incrusting masses of laminated 

 structure, but occurs also in the ramose form, which latter is only 

 with diflS.culty distinguished from a second subgenus, the 



Limaria or Cladopora, Siriaiopora and Coemtes, all of whictx 

 names are designed for fossils of the same organization. 



Limaria is a Calamopora growing in small branches, with very 

 massive tube- walls, and expanded cell-mouths of rounded or trans- 

 versal ly elongated shape. Its side pores are large and not nu- 

 merous, its tubes augment by interpolation, sometimes opening 

 at their lower ends into the side- walls of older tubes, as m 

 Alveolites. Transverse diaphragms perfect, or represented Dy 

 lateral lingaiform projections, but frequently wanting. . 



Cladopora is said to differ from Limaria by a different shape oi 

 tlie orifices, but it is impossible to draw a line of division between 

 the different forms. 



