68 SIXTEENTH REPORT ON THE CABINET OF NAT. HISTORY. 



more rapidly downwards to the periphery : its thickness, so far 

 as observed, is from one-eighth to about half an inch, with a dia- 

 meter of three to four or five inches. The pores are smaller than 

 in R. neptuni, and nearly the same as in R. iowensis. 

 The species is described by Eaton as follows : 



" Coscinopora infundihuliformis ( funnel net stone). Funnel-forms 

 " perforated at the bottom : little mouths arranged in the form 

 *' of numerous arcs of circles crossing each other obliquely, by 

 " having their centres considerably distant. I have a beautiful 

 " specimen two and a half inches by three and a half, from the 

 " Greywacke, with the C. macropora.^^ 



The figures given for illustrating the species offer a very, im- 

 perfect representation of its characters. 



In addition to the preceding, we have a species in the Schoharie 

 grit, which is of the same size as the R. iowensis^ or larger, and 

 with much larger cells. The form is depressed-orbicular, but fre- 

 quently not equally developed around the organic centre, which is 

 abruptly depressed. In two specimens before me, one is a regular 

 depressed spheroid, having a lateral diameter of an inch and a 

 half, with a vertical height of three-fourths of an inch ; while the 

 other, an imperfect specimen, measures one inch and a half on one 

 side of the central depression. 



It is possible that this may be the Coscinopora sulcata of Eaton 

 (Geological Text-book, p. 44) ; but the description "apertures of 

 pores within rhomboidal, without orbicular," is inapplicable to 

 the specimens which I have seen. The aspect of this species is 

 very similar to the figures of Ischadites, Koeniger ( Murchison's 

 Silurian System and Siluria, pi. 12, f.),, which has been identified 

 with Receptaculites neptuni of De France by British palasontolo- 

 gists. 



We are therefore able to trace the occurrence of this remark- 

 able genus from the Lower Silurian to the Devonian period, in the 

 following species : 



Receptaculites ? Schoharie grit, Devonian. 



infundihuliformis, Eaton: Lower Helderberg group. ' 

 infundibulum,B.ALL: Niagara group. 



hemisphericus , 



suhturhinatus , . . . . . . / ^ 



02 



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