AMOKPHOZOA FROM THE SILURIAN AND DEVONIAN. 247 



stead of forming extended crusts, as the latter species does, S. ponderosa 

 constitutes a ponderous and compact sub-spheric mass. 2. The surface 

 is not simply undulated, but exhibits also prominent, rounded, nipple- 

 shaped eminences, the disposition of which is very irregular. 3. The 

 large apertures ("oscula") are much larger than they are in S. tuberculata 

 (twice the size or more), and are arranged in small groups of two or three. 

 4. The tubercles which cover the surface are smaller, and are always dis- 

 tinct and separate from one another. 5. The laminated tissue is closer, 

 and the concentric laminae more delicate. 



There can be little doubt as to the propriety of referring S. ponderosa 

 to the Sponges. The surface not only exhibits groups of large rounded 

 apertures or "oscula," but also numerous minute openings perforating 

 the surface-tubercles, and doubtless corresponding with the " pores." The 

 perforation of the surface-tubercles would lead to the supposition that 

 the similar eminences in S. tuberculata (as I previously conjectured) are 

 likewise j^erforated, and are also of the nature of " j)ores." This suppo- 

 sition, however, does not rest upon the analogy derived from S. ponderosa^ 

 for I have recently obtained magnificent specimens of *S'. tuberculata show- 

 ing that many of the surface-tubercles have their apices very distinctly 

 perforated. 



The only specimen which I have seen of S. ponderosa is a large sub- 

 spherical mass, cut in half and polished on one side. The mass is im- 

 perfect, but its vertical height is over five inches, and its transverse 

 diameter must have exceeded half a foot when complete. Its base is 

 broken, and its method of attachment is therefore unknown. The sur- 

 face exhibits nine oscula, arranged in two groups, which are placed about 

 an inch and a half apart. 



Position and locality : Corniferous limestone, Kelley's Island, Ohio. 



Stromatopora concentrica, Goldfuss. (?) 



Stromatopora concentrica, Goldfuss ; Petref., pi. 8, fig. 5. 

 Stromatopora concentrica, Phillips ; Pal. Foss., pi. 10, fig. 28. 

 Stromatopora concentrica, McCoy; Pal. Foss., p. 65. 



The Corniferous limestone of Ohio yields specimens which may with 

 much probability be referred to this classical species, but as the examples 

 in question exhibit no part of the actual surface, any thing like absolute 

 certainty of identification is rendered an impossibility. The reticula- 

 tion and lamination of the specimens would, however, agree tolerably 

 with that of S. concentrica^ Gold, (though not so coarse), and the various 



