44 JPROCEEDINGS OF THfe ACADEMY OF [1886. 



As representing this kind of channels, or oscula, as they term 

 them, the authors mention the following forms : Stromatopora 

 striatella^ Hindei^ tuherculata^ ponderosa, and ostiolata. In the 

 first four mentioned forms, the true nature of these perfora- 

 tions is without difficulty demonstrable. In St. ostiolata^ of which 

 specimens from Guelph, Canada, are transformed into a coarsely 

 crystalline dolomite, the organic structure of these masses can 

 scarcely be ascertained, and it is impossible to decide definitely 

 on the nature of the tubular casts traversing them. One of the 

 other examples mentioned, the so-called Stromatopora Hittdei, is 

 unfortunately selected, as it is in reality an Alveolites^ perforated 

 by some boring animal. The figures and description given leave 

 no doubt as to this point. Similar silicified specimens are, more- 

 over, not rarely met with in the Niagara group of Michigan. 



The second kind of vertical tubular channels supposed to have 

 the function of conducting water through the organism of Stro- 

 matopora has distinct walls with imbricating wrinkles of growth 

 on the outside, and frequently from their interior a circle of 

 longitudinal rows of spinules projects ; more rarely invaginated 

 funnel-shaped diaphragms interrupting the tube-channels can be 

 observed, all of which proves that we have before us inclosed 

 stems of a Syringopora and not canals making part of the skele- 

 ton of the associated Stromatopora. Specimens of each are quite 

 abundant in the Devonian strata of Michigan, Ohio, Kentucky, 

 and Canada. Some pebbles found on the shore of Lake Superior 

 represent the same parasitical investment of clusters of Syringo- 

 pora stems on Stromatopora. 



In the Niagara group we also find various kinds of Stromato- 

 pora similarly intergrown with stems of a delicate Syringopora, 

 which I have described in the Michigan Geological reports under 

 the name Syringopora filiformis. In other cases we find colonies 

 of Diphyphyllum multicaule invested in the same way by Stroma- 

 topora. 



In this connection also Stromatocerium of Hall is cited by the 

 authors as an example of the first class of vertical water canals, 

 without any proper walls. In a chapter headed '' Departures from, 

 the Ordinary Type of Stromatopora,^'' as the first of these, Stroma- 

 tocerium, is enumerated, and the following description given : "It 

 has the general aspect of Stromatopora, and possesses crowded con- 

 centric laminae characteristic for Stromatoporoids. The laminae are 



