48 



"Body globuse or subglobuse, with an irregular base of attach- 

 ment; transverse diameter usually greater than the vertical diam- 

 eter; summit a little depressed; cells arranged in radiating curved 

 lines, the apertures rhomboidal and transversely elongated; con- 

 centric groove and raised ridges between strongly marked. This 

 species is readily distinguished by its small globose form, which 

 is usually not more than three-fourths of an inch in diameter. It 

 is more rare than either of the others (i?. owetii and R. iowensis) 

 though I am informed by Prof. Daniels, that more than twenty 

 specimens were obtained at a single locality in Wisconsin. About 

 twenty years since, I received a specimen of this species from Mr. 

 Thorp, of Mount Morris, Illinois, and have seen others in Galena, 

 and in the collection of Prof. Daniels. Geological formation aud 

 locality. — In the Galena limestone of the lead region of Wiscon- 

 sin, Iowa and Illinois." 



The name and definition might have passed into oblivion, because 

 no one could have recognized the species, if Prof. Meek had not 

 revived it, in the Geological Survey of Illinois, vol. 3, p. 301, pi. 

 2, fig. 2a, h. Prof. Meek described under the name of Recepta- 

 cnliies (jlohidaris, Hall, a species as follows: 



"Body obovate, or subglobose, rounded and slightly umbilicated 

 above, and tapering to a rather broad base of attachment below. 

 Cells arranged in the usual regularly curved lines, with transversely 

 elongated rhomboidal apertures, which become exceedingly narrow 

 aud crowded on the sides; transverse ridges between the cells and 

 the intervening grooves well defined, and becoming, like the cells, 

 very closely compacted together on the sides. This is probably 

 the form described by Prof. Hall, under the above name, though 

 it is proportionally longer than the specimens upon which the 

 species was founded, which are said to be usually wider than long. 

 Wo have others, however, from the same locality agreeing more 

 nearly with his description, and apparently not separable specifi- 

 cally from this. Locality and position. —Scales' Mound, Illinois; 

 from the Galena division of the Lower Silurian series." 



We have never seen a sp(»cimeu that resembles the definition 

 given by Prof. Hall, making due allowance for the fact that he 

 called the summit the base; which was an excusable mistake, until 

 after the study of Billings, on Eeceptaculites, published in 1865, 

 in Palffiozoic Fossils, p. 378. But the species illustrated by Prof. 

 Meek will stand for that of Hall, and we come now to compare it 



