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species, and not to Gr. (jcographlca ; now Gray calls it also Emus pseudo- 

 (jeographica" Since that time Prof. E. D. Cope, in his Check List of 1875, 

 employed the name used by Holbrook, but ISlr. F. W. True, in Dr. Yar- 

 row's Check List of 1S82, adopted Agassiz's suggestion and called the spe- 

 cies MahACoclemys hioieurii. 



Since now the name by which we are to know the species called by Le 

 Sueur and Holbrook psendogcographica depends on what Gray had before 

 him when he described his Emiis lesuenrii it becomes necessary, if possible, 

 to determine that matter. More certainly depends on that than on Gray's 

 references to any previous writings. 



Among other differt-nces existing between the two species of 31<daclemi/s 

 referred to here, is one which enables us in all cases to distinguish them. 

 This is found in the form of the yellow spot which lies on the side of the 

 head just behind the eye. In M. geograpldm this spot is broad, rather tri- 

 angular, and elongated in the direction of the head. In the other species 

 the spot is a transverse streak, running behind the eye and sometimes curv- 

 ing forward below it. Now, in his description of Einy» lesueurii, Gray has 

 this language : " Temporibus macula triangulari notatis." At the end of 

 his description he further says: '^ Emys geographica of Le Sueur agrees 

 with the museum specimen, except in that the first vertebral plate is not 

 urn- shaped, and Le Sueur does not notice the triangular temporal spot." 

 In that remark we have evidence that Gray had before him but a single 

 specimen and that that specimen had the " ear-mark " of geographica. We 

 further learn why he described it as different from Le Sueur's species. 

 That Gray was at this time aware of the existence of Le Sueur's manu- 

 script name appears from the following words at the end of the descrip- 

 tion: 



'' ;5 Scutello vertebral! primo urceolato." Emys geographica. Lesueur. Jour. Acad. 

 N. S. Phil. t. £?»j/.sj).sewdo(jfeo£fr«jj/aca, Lesueur Mss. (Mus. Paris). 



This is probably the reference that Agassiz alludes to, and it is hard to 

 see why Gray introduces it here; but it no more proves that he had Le 

 Snenr^s pseud ()g(vgra2)hic( I in mind than the other species. Indeed, he re- 

 garded them as both the game thing. Furthermore, in his Catalogue of the 

 Shield Reptiles, he refers this ^5 to jisrudogeogrdphicn, while his lesuexrii is re- 

 ferred to geograpliiv'i. It is evident that he regarded what he placed under 

 yj as different from the species he was describing. I make the suggestion 

 that the quotation marks were put in front of the ^j through an error of 

 writing or printing. As to the characters assigned to lesueurii, I submit 

 that they apply much better to M. geograplnca than to p><eudngeographica. 



