1870.] ^^^ [Winchell. 



with the presence of Producta and various forms of hind vegetation, in 

 impai'ting to that group, to tliis extent, a Carboniferous aspect. '^s 



The genus Mytilu><, of which we know four species in the Marshall group, 

 is decidedly one whose history I'uns through later geological times. Of 

 303 species enumerated by D'Orbignj^, only 12 are recognized as occur- 

 ring in rocks older than the Carboniferous, and it is probable that some of 

 these belong to Modiolopsis and Orthonota or allied genera. 



The genus Myalina was established by De Koninck exclusively to re- 

 ceive three species from the upper part of the Coal measures of Belgium. 

 ivicCoy discovered none below the Permian system. In this country the 

 genus is restricted to the limits of the Carboniferous system, attaining its 

 maximum development in the Coal measures. Of this Carboniferous ge- 

 nus the Marshall group affords at least 5 species. 



Edmondia, also founded for the reception of Carboniferous forms, has 

 not been certainly traced downwards into the limits of the Devonian sys- 

 tem. De Koninck gives two species, both from the Coal measures ; Mc 

 Coy, in the work cited, describes 10, all of which occur in the Carbonif- 

 erous Limestone. The Marshall group has afibrded 9 species which have 

 been referred to this genus. 



Sanguinolites of McCoy afforded its i^roposer 14 species, of which 11 

 occur in the Carboniferous strata, and 3 in rocks of older date. In the 

 Marshall group we recognize 19 species of this genus, including 5 belong- 

 ing to the type of Cypricardia. 



The genus Cardiomorpha is, iu the Old World, confined exclusively to 

 the Carboniferous System, from which De Koninck describes 13 Belgian 

 species, and McCoy 3 British species. We have described 5 species from 

 the Marshall group, and know of none from the Chemung. 



Nine species of trilobites have been described from the Marshall group, 

 all of which probably belong to the Carboniferous genus Plhillipsia, 

 though five of them were referred to Proettis by their original describers. 

 Of the latter five, Proetus elUptieus, M. & W. was thought by the authors to 

 be probably a Phillipsia. Proetus Swallowi, !Shum. is regarded as the near- 

 est analogue of this, and the latter is hence probably also a Phillipsia, 

 This species, moreover, does not present the posterior termination of the 

 great suture required by Proetus. Proetus Boris, Hall, was described 

 from pygidia, and of course its generic relations are not demonstrated. I 

 have since discovered from the same locality, several complete cephalic 

 shields which present the distinctive marks of Phillipsia, so far as they 

 have been pointed out. All the Carboniferous trilobites of Europe and 

 America belong to this genus and its sub-genus Oriffithides. Though Bar- 

 rande inclines to recognize Phillipsia sparingly in the upper Silurian and 

 Devonian, we are still compelled to regard it as an eminently Carbonifer- 

 ous tyi^e. 



"'As has been already intimated several Carboniferous typjs began their existence as early as 

 the Hamilton and even the Corniferous period. Several of the Fenesteltidce from the Hamilton 

 rocks of Michigan were identified by Dr. H. A. Prout with species in the Carboniferous Lime- 

 stone. His worlc upon these fossils was incomplete at his death, and has never been pub- 

 lished. 



A. P. S. — VOL. XI. — 23e 



