156 CATALOGUE OF THE BLASTOIDEA. 



to appear shorter on the internal cast than on the exterior of the calyx, as is 

 well shown on PI. III. fig. 4. Hambach 1 figures a specimen of P. sulcatus which 

 illustrates this point very well ; but we think that he is wrong in identifying this 

 internal cast of P. sulcatus with that which was described as P. laterniformis by 

 Owen and Shumard 2 . The latter is a much higher cast than the one figured by 

 Hambach, who does not appear to be aware that the appearance presented by 

 P. laterniformis may be repeated in casts of other species besides P. sulcatus. 



Species. For us to give a full and at the same time anything like an accurate list of 

 the species of Pentremites would be an impossibility. We are convinced that many 

 synonyms exist, but as the genus is so essentially an American one and is limited to 

 the Subcnrboniferous, we must leave to some Palaeontologist of that country the task 

 of unravelling this perplexing subject. At present we intend to indicate only those 

 species with which we believe ourselves to be personally acquainted. 



Pentremites angularis, Lyon. Chester Group ; Illinois and Kentucky. 



Pentremites Burlingtonensis, M. & W. Burlington Limestone; Iowa. 



Pentremites conoideus, Hall. Warsaw Limestone ; Indiana. 



Pentremites conoideus, var. Koninckanus, Hall. Warsaw Limestone ; Indiana. 



Pentremites elegans, Lyon. Kaskaskia Limestone ; Illinois. 



Pentremites elongatus, Shumard. Burlington Limestone ; Iowa. 



Pentremites gemmiformis, Hambach. Kaskaskia Limestone; Illinois. 



Pentremites globosus (Troost), Hall. Kaskaskia Limestone ; Illinois. 



Pentremites Godoni, Defiance. Kaskaskia Limestone ; Alabama, &c. 



Pentremites Godoni, var. abbreviatus, Hambach. Kaskaskia Limestone ; Illinois. 



Pentremites Godoni, var. fiorealis, von Schlotheim. Kaskaskia Limestone ; 



Alabama. 



Pentremites Godoni, var. major, E. & C. Kaskaskia Limestone ; Tennessee. 



Pentremites hemisphericus, Hambach. Kaskaskia Limestone ; Illinois. 



Pentremites obesus, Lyon. Kaskaskia Limestone ; Kentucky. 



Pentremites piriformis, Say. Kaskaskia Limestone; Alabama, &c. 



Pentremites pyriformis, var. sijmmetricus, Hall. Ibid. ; Kentucky. 



Pentremites robustus, Lyon. Chester Group ; Illinois and Kentucky. 



Pentremites sulcatus, Roemer. Kaskaskia Limestone ; Illinois. 

 Distribution. The genus Pentremites, as restricted by us, is essentially Carboniferous 

 and strictly American, with one possible exception. We refer to P. oralis, Goldfuss 3 , 

 a form witli which we are unfortunately not acquainted. It was said to come from the 

 Transition Limestone (Devonian) of Cromford, near Ratingcn, Diisseldorf ; and our 

 friend Professor P. Roemer informs us, that though obtained from a large quarry of 

 Carboniferous Limestone it was found " not in the thick bedded Carboniferous Lime- 



1 Trans. St. Louis Acad. Sci. 1880, vol. iv. no. 1, p. 147, pi. B. fig. 10. 



: Wisconsin, Iowa, and Minnesota Geol. Report, 1852, p. 5'J2, tab. Vo. fig. 15. 



3 Petrefacta Germanise, 182G, Theil i. p. 161. 



