December 3, 1915] 



SCIENCE 



797 



tions between the lesser natural groups are 

 relevant to the subject under discussion. 



It is difficult to see, in the case of Sciurus, 

 or any other group, that we are any better off 

 when we have divided all our species into 

 numerous geographical (and other) species, 

 and have called the old species genera, of 

 course changing the names in the process, 

 than we are when we retain the old species, 

 calling their now recognized subdivisions sub- 

 species, races and forms, and treat as sub- 

 genera rather than genera newly discerned 

 natural groups of species within the old 

 genus. Of course, an old genus, if shown to be 

 unsound and to express a false concept of rela- 

 tionship, will be abandoned. 



There is almost no limit to the niceties of 

 taxonomic analysis that might be introduced 

 by breeding of all animal species. Any classi- 

 fication short of one founded on such complete 

 data is conventional. The practical question 

 is, what convention shall we adopt? The one 

 here advocated retains, in so far as they are 

 valid, old genus and species names, using a 

 subsidiary nomenclature of subgenera, sub- 

 species, etc., for the more intimate distinctions. 



There are several advantages in this course. 

 It does not change general conceptions of 

 genus and species to something of a different 

 grade of taxonomic value. It keeps us in touch 

 with the zoology of the past (i. e., that of year 

 before last). It saves immense labor in ascer- 

 taining what forms are meant by the unfamil- 

 iar names when one is reading outside his 

 special field. It ensures more general imder- 

 standing by one's readers. It does not limit 

 completeness of taxonomic analysis, which is 

 recorded in the subsidiary nomenclature. It 

 confines to the field of the specialist, who 

 uses the subsidiary nomenclature only when 

 writing for his fellow specialist, most of the 

 confusion which comes from the acceptance 

 and later the rejection of imjustified terminol- 

 ogy. It thus saves the general literature of 

 zoology from the introduction of an immense 

 deal of confusion. 



Maynard M. Metcalp 



The Orchard Laboratory, 

 Oberlin, Ohio, 

 October 26, 1915 



NOTES ON THE PERMO-CARBONIPEROUS GENUS 

 CRICOTUS COPE 



In Publication N"o. 207 of the Carnegie In- 

 stitution of Washington I described and 

 figured an ilium from the Brier Creek Bone 

 Bed of the Wichita Formation in Archer Co., 

 Texas (page 161, pi. 22, figs. 2 and 3). This 

 bone was assigned to the genus Cricotus be- 

 cause of the relative abundance of the speci- 

 mens associated with large numbers of the 

 vertebral and intervertebral centra of that 

 genus. The peculiar form of the ilium, uni- 

 que and previously unknown from the IN'orth 

 American beds, makes it of peculiar value in 

 correlating faunas of widely separated local- 

 ities. In looking over Fritsch's " Fauna der 

 Gaskohle " I find an almost identical form of 

 this bone described and figured for two genera, 

 Diplovertehron^ and Macromerion.' Fritsch 

 recognized these elements as ilia but in some 

 figures confuses parts of the bones with the 

 ischia and pubes. It is at once obvious from 

 a comparison of his figures with those pub- 

 lished by me that the bones from the two widely 

 separated localities are nearly identical, even 

 to the smallest details. Unfortunately the 

 ischia and pubes of the Bohemian forms were 

 only partly known to Fritsch and he publishes 

 figures of fragments only. 



The two Bohemian genera, from the upper 

 Carboniferous, are embolomerous forms and 

 many of the bones figured by Fritsch as asso- 

 ciated with the ilia are strikingly like those 

 assigned to Cricotus from the Brier Creek 

 Bone Bed, notably the femur and the smaller 

 bones of the limbs. The inter-centra of 

 Macromerion schivarzenbergii^ are indistin- 

 guishable from those of Cricotus. The teeth 

 also show many resemblances in the two types, 

 especially in the manner of fixation to the jaw 

 and the slightly infolded dentine of the base. 



There can remain no doubt that the family 

 Cricotidse was present in Bohemia and North 

 America at nearly the same time and was rep- 

 resented by closely related genera. This adds 



1 Bd. 11, Taf. 52, Fig. 2 and Taf. 53, Fig. 14. 



2 Bd. 11, Taf. 6, Figs. 1, 2; Taf. 67, Figs. 1, 2; 

 Taf. 69, Fig. 1. 



3 Taf. 66, Figs. 5a, 6, c. 



