32 



and M. glohosa^ Pander, to which the name JScmipronites 

 might be applied if they prove distinct from any group 

 named before 1830^ and which, under Pander's name, were 

 thus separated as a section of Orthis by Bronn In 1849 (iii, 

 p. 228). To this it may be objected that the first species is 

 represented by an unrecognizable cast of the interior, and 

 the second bears considerable resemblance, as far as the 

 figure is concerned, to a species of Forambonites. I shall 

 therefore consider H. tumida and vars. as forming the typical 

 species. 



Quenstedt (Petr. Deutschl. 1871, p. 545, t. 55, f. 32-34) 

 has figured the interior of what he states to be this species, 

 which he regards as one of his somewhat heterogeneous 

 group of Orthides, and affiliates to Orthisina, D'Orb. ( = 

 Klitamhonites). The character of this interior does not ap- 

 pear to differ materially from that of Klitamhonites, but, in 

 deciding, much will depend on the view taken by each indi- 

 vidual paleontologist as to the value of characters which 

 appear to vary as much within the species as do the so- 

 called generic characters between different groups of species. 

 According to Quenstedt's figures, the difference between 0. 

 hemipronites {= tumida, tyi^e of Hemipronites) and 0. ano- 

 mala [— adscendens, teste Quenstedt, type of Klitamhonites 

 and first species of Orthisina, D'Orb.) is merely a question of 

 degree of breadth of area and prolongation of the median 

 ventral septum. 0. plana seems to be of very similar type. 

 For present purposes, it will suffice to regard Hemipronites 

 and Orthisina as synonyms of Klitamhonites, leaving to 

 paleontologists the duty of determining whether there are 

 grounds for ultimate separation of the species which they 

 contain. 



Now Davidson and some other authors have (as it seems 

 to the writer), with evident propriety, taken Blainville's sole 

 species (S. rugosa) as the type of the genus StropJiomena, of 

 which Blainville alone can be considered as the author ; this 

 species is generally admitted to be the same as S. planum- 

 bona, Hall, figured by Meek in the Paleontology of Ohio, i, p. 

 74, pi. 6, f. 3 a-g, 1873, and by Davidson, 1856, t. xi, f. 37-39. 



In 1843, Vanuxem f Geol. Kep. Third Distr. N. York, p. 124, 



