12 INTRODUCTION. 



For further remarks, see cotype. 



IvBCTotype (new).— Where the original diagnosis is without illus- 

 trations or is accompanied by figures based on two or more specimens, 

 the first subsequent author is at liberty to select from these cotypes a 

 type for the old species, adhering, as far as can be ascertained, to the 

 intention of the original author. Such a type specimen is to be desig- 

 nated as a LECTOTYPE ( = a chosen type). From the remaining cotypes, 

 or from other material in his possession, he may select the holotype or 

 cotypes of his new species. 



ChiroType (new). — This term is proposed for the material upon 

 which a published manuscript name is based. It is a term equal in 

 value to "Chironym: A manuscript name; an unpublished name." 8 

 The former applies to specimens, the latter to the written name. Just 

 as soon as a chirotype is properly published, the term will no longer 

 apply to it, and the material will become either a holot3^pe, paratj^pe, or 

 cotype. 



SUPPLEMENTARY TYPES. 



PLESIOTYPE. — Cossmann b first proposed this term with two meanings, 

 which Buckman, in a letter to the writer, summarizes as follows: 



i. A species akin to the monotype representative of the genus at another geological 

 horizon or in another zoological province. 



2. A specimen, not a topotype, figured ct described as an example of an already 

 named species. 



In 1904, Cossmann redefined this term in accordance with his second 

 meaning, and it is in this sense that the present writer uses it in this 

 catalogue. He states: 



An individual [of a described form], whether from the same localitj' or from 

 another deposit, which one compares with a species and for which one gives a new 

 description and a new figure, is a plesiotype of that species. 



In 1S97, Schuchert proposed for identical material the term Hypo- 

 type, which is therefore a synonym of Cossmann's name. Further, 

 hypotype is in use with another meaning: "Subtypical; not quite 

 typical." (Cent. Diet.) 



Thomas'' thinks this term (hypotype = plesiotype) "too general to be 

 of much definite use." This criticism has also been made by others, 

 but the writer fails to see what can be gained by dividing these supple- 

 mentary types into different categories. After all, it is the primary 

 types on which the taxonomy rests, and the supplementary types (plesio- 

 tj-pes) simply help to elucidate the original material. The only other 

 kind of supplementary types worthy of distinction are those selected 

 plesiotypes on which the species will rest when the original types are 

 lost, destroyed, or inadequate for the determination of the specific char- 

 acters. These have been named by Cossmann Neotypes. 



« Cones. Auk. IX. 1SS4, p. 321. 



&Essais de Palebconchologie cotnparee, 1896, pp. 2, 3. 



f Science, Sept. 24, 1S97 p. 486. 



