Clarke — The Naples Fauna. 



101 



during the progress of the survey of the Fourth District ; some of these have 

 the sutures of Probe!. Lutheri, and the others show only the exterior. Sub- 

 sequent identifications of this species afford little assistance as to its essential 

 characters. 



In the Fifteenth Ann. Kept. N. Y. State Cab. (1861), p. 63, the species 

 was redescribed, but nothing added as to its internal structure. It is here 

 stated to be found in the green shales of Cashaqua creek, and in the 

 Hamilton group at Eighteen-mile creek. In the same work, the species 

 Chjmenia Erato is described (p. 64), and figured (pi. 10, fig. 1). This is of 

 similar character to the C. complanata, but is also given without details of 

 interior structure. It is recorded as from the Hamilton group at Geneseo, 

 and at Patterson's creek near Moscow. 



The Palaeontology of New York, vol. v, pt. 2, p. 455 (1879), gives 

 what was then known concerning the shell. The sutures are here described 

 in the following terms : " Rising from the axis, they make a gentle retral 

 bend and are recurved toward the aperture from a point about one-third 

 the width of the volution from the umbilical margin, describing a shallow 

 lateral lobe ; thence arching more abruptly, they include a more elevated 

 lateral saddle, the apex of which is at a point about two-thirds the width 

 of the volution from the umbilical margin. From this point the septa 

 arch backward, limiting a narrow, acute lobe on the peripheral margin/ 1 

 This description has evidently been derived from the specimen figured upon 

 pi. lxx (fig. 8), which presents an apparently immature manticoceran suture, 

 totally unlike anything observed by us among these forms. This specimen 

 seems to us to be a worn or macerated example of Mantle. Patterson), in 

 which the wear has been carried inward to the extent of rounding the lobes. 

 It is refigured uuder the same name in the Supplement to the same work 

 (vol. vii), pi. exxvii, fig. 2, but without modification of the sutures. In 

 reference to the fossils of the Portage group, it has been usual to refer 

 to Gon. complanatits, the very common discoid specimens in which the shales 

 abound. The writer has himself thus identified such specimens* and has also 

 fallen into the error of describing as the suture of this Gon. oomplcmatus, that 

 of a macerated Mantic. Pattersoni. As it is now evident that such discoidal 

 specimens may represent quite different species, and there is no way of know- 

 ing to which of these the original of Gon. comjylanatus belongs, we have 

 felt compelled to set aside the name, or to reserve it against further study 

 of the original whenever that shall have been found. 



•Bull. U. S. Geol. Surv. No. 10, pp. 47, 48. 



