KO. 2225. NVCULITES FROM TEE MAINE SILURIAN— WILLIAMS. 53 



In the present case I have taken pains to bring together the mor- 

 phological characters with the evidences of metamorphism exhibited 

 by the shales in which they lie so as to demonstrate the real cause of 

 the specific form. 



The evidence of metamorphism is mostly obliterated, when the 

 specimens have been detached and trimmed for the museum, and is 

 entirely absent in the ordinary figures by which the fossil species are 

 illustrated. 



In order to distinguish such species from those fossil species which 

 preserve their original characters, I propose to call them metamor- 

 PHic SPECIES, using the word metamorphic in the sense proposed in 

 the Rules of Nomenclature and Classification adopted by the United 

 States Geological Survey in 1903. In these Rules the following defini- 

 tion is given: "Metamorphic including altered rocTcs of either sedimen- 

 tary or igneous origin in which the acquired are more prominent than 

 he original characteristics.'^ 



The species of the splintery shales of Kelley Point are metamorphic 

 species in this sense that the acquired are more prominent than the 

 original characteristics. With this definition in mind the paleontol- 

 ogist will be able to remove a large number of fossil species from zoo- 

 logical nomenclature, and place them in a category by themselves 

 for the special use of the geologist. 



In the present paper I have assigned names selected from classical 

 mythology to those species which seem to me to come under this 

 definition of metamorphic species. They are of importance to the 

 paleontologist in defining the fossil contents of formations and the 

 characteristic expression of the faunas of particular localities. But 

 they have no legitimate place in zoological nomenclature as species 

 or varieties, although their generic characters may be cited whenever 

 these characters have not been obUterated by the metamorphic 

 processes. 



EXPLANATION OF PLATES. 

 Plate 11. 



The figures on this plate are all natural size. 



The arrangement of the figures is designed to illustrate the effects of distortion by 

 which the original form of the shells has been obscured or entirely obliterated. 



Figure 19 is an elongated slab of the splintery shale from locality 5.3.2. A showing 

 the specimens, illustrated in figures 1, 2, 3, and 4, as they lie upon the surface of the 

 slab; the separate figures have been rearranged to correspond to the ordinary mode 

 of representing such figures upon a plate. 



The original orientation of these specimens is indicated by the lines, drawn across 

 them, which represent the long axis of the slab on which they lie. 



