288 PALEONTOLOGY OF NEW YORK. 



it be found desirable or important to recognize the value of the characters above 

 indicated, these forms may be separated under the term Leptostrophia. 



As typical representatives of this group, may be taken S. magnifica, Hall, of 

 the Oriskany sandstone, and S. perplana, Conrad, of the Corniferous, Hamilton 

 and Chemung faunas ; and of the other American representatives we may cite 

 S. textilis. Hall, of the Coralline limestone, S. Becki, Hall, of the Lower Helder- 

 berg, S. magniventra, Hall, of the Oriskany, S. Junia, Hall, of the Hamilton, S. 

 Irene, S. BlainviUii and S. Tullia, Billings, from the Lower Devonian of Gaspe. 

 In European faunas the group is represented by Strophomena filosa, (Sowerby) 

 Davidson, of the Wenlock, S. explanata, (Sowerby) Kayser, of the Coblenzian, 

 S. ? palma, Kayser, of the Calceola beds, and S. Steini, Kayser, of the WieJaer- 

 schiefer (Lower Devonian) of the Hartz 



There is a small number of species, the incipient members of the genus 

 Stropheodonta, in which the delthyrium is open, or but partially covered, as 

 in some of its later forms, the crenulations are confined to a very limited ex- 

 tent on either side of the deltidium, and upon one of these forms, Strophomena 

 Leda, Billings, from the Anticosti group, Professor 

 Shaler has proposed to found* the genus Brachyprion. 

 To the same group belong the Strophomena Philomela, 

 Billings, from the Pentamerus ohlongus beds of Anticosti, 

 and Professor Shaler has described two other species 

 from Anticosti, Brachyprion ventricosum and B. genicula- kki.ji. itnnum'rio,, i.e,i,i 

 turn. These features can scarcely be regarded as of 



•generic value, but the group is an interesting one on account of its being the 

 precursor of the fuller development of those characters on which the genus 

 Stropheodonta was originally founded. 



Dr. CEhlert has proposed the generic term DouvrLLiNA,f for the species 

 Leptcena Dutertrii, Murchison,| evidently not fully apprehending its very close 



* Bulletin of ti. 'i . - i (Comparative Zoology, vol. i, p. 63. 1865. 



t In Fischer's Manuel de Conchyliologie ; Brachioj>odes, p. 1282. 1887. 



t See DE Vebneuil, Geologie ile la Russie, etc., p. 223, pi. xiv, figs. 2 a, b, c. V\g. 4 of the same plate 

 represents an interior closely similar to that figured by CEhlkrt, and in the explanation of plate is referreil 

 to L. Dutertrii, but on page 224 is regarded as belonging to L. asella, de Veriieuil. In this cjiae the latter 



