DESCKIPTIONS OF SPECIES. 389 



of the Coal Measures. " Now, it is evident that internally the shells included vinder 

 JReticularia by McCoy are very different from those which the usage of Waagen and 

 of Hall and Clarke embrace. McCoy in 1854, commenting upon Spirifer lineatus, 

 sj)eaks again of the dental lamella and septa of Reticulariava. the following terms: 



"This species, from the peculiar structure of the surface and the slight divergence 

 of the dental lamellae with their strong mesial septum, was originally combined in 

 my Synopsis (of Carb. Foss.) with the S. imiricata, S. 7'eticuJata, S. microgemma, 

 etc., into a little group called Heticxilaria. There is a fine submedial impressed 

 line, apparently a fracture, visible in many specimens from the beak to the front 

 margin."" 



Waagen, after quoting this passage, says: 



" Now, it does not seem to me probable that the British specimens of Reticula/ria 

 possess an internal structure different from that of the specimens from Vis^, with 

 which the Indian specimens entireh' agree. It seems far more probable that there 

 has occurred a mingling of different things by McCoy, and that he described the 

 above characters from a specimen of Martiniopsis, or something like it. Neverthe- 

 less, it would be very desirable to learn more particularlj'' about these British fossils."* 



Examining our American species of this type, I find that the Mississippian 

 forms, without exception, so far as my examination goes, possess internal structures 

 as described hj McCoy, while the Upper Carboniferous ones are structureless, as in 

 the group described by Waagen and by Hall and Clarke. The species referred to 

 Eetlcularia by McCoy were found in strata of the age of our Mississippian series, 

 while Waagen's material from India came from high up in the Upper Carboniferous, 

 or Permian. It thus appears that the groups of shells characterized by these internal 

 differences are characterized also by a difference of occurrence in the geologic 

 column. Hall and Clarke e\adently handled species of both stratigraphic occurrences 

 and representatives of both types of internal structure, but apparently they passed 

 over these, to me, important distinctions in favor of a certain agreement in general 

 external expression. 



I think there can be no doubt to which group the term Reticnda/ria was originally 

 applied, and I propose to restrict it to the original implication and to emploj' a 

 distinct term for the shells without septa or dental lamella?, as Waagen has described 

 Reticularia. 



I had, in manuscript, proposed for this group a distinctive name, when there 

 came into my hands a work by Gemmellaro,'' in which he proposes the name 

 Squam ularia for some fossils very similar to those which it was my purpose to 

 include in a new genus. A full and, in the main, literal translation of Gemmellaro's 

 remarks upon SquawMlaria is here appended. 



a British Paleozoic Rocks and Fossils, Sedgwick and McCoy, Cambridge, 1854, p. 430. 



SLoc. cit., p. 638. 



cLa Fauna dei Calcari con Fusulina, fasc. 4, pt. 1, p. 3'25, Palermo, 1898-99. 



