I go I.] Gidle}\ The North American Species of Equiis. 



117 



If these Silver Lake specimens can be regarded as representative 

 of E. pacificus as described by Leidy, this species can now be 



B 



Fig. II. Equus pacificus. A. superior fourth premolar, p* (No. 8602, Coll. A. M. N. H.) ; 

 -5, superior third premolar, p2( No. 8601, Coll. A. M. N. H.) ; C", superior second molar, m- 

 (No. 8603, Coll. A. M. N. H.) 



pretty clearly defined. Figure ii, A^ B, C (Nos. 8601, 8602, 

 and 8603, Coll. Am. Museum Nat. Hist.), are representative teeth 

 of the Oregon collection. Their measurements are as follows: 



(No. 8601) p^ 

 (No. 8602) Y>- 

 (No. 8603) m^ 



^ Antero-posterior diameter 35 



( Transverse " 



( Antero-posterior " 



( Transverse " 



( Antero-posterior " 



( Transverse " 



34 



34-5 

 32.5 

 32.5 

 31 



The collection above referred to was briefly but not accurately 

 described by Cope. Careful measurements of the bones in this 

 collection show that the astragalus and other bones of the feet 

 that can be identified as fully adult are not smaller than in E. 

 caballus, as stated by Cope, but compare in size with the large 

 draught horse. Also he is probably mistaken in the statement 

 that " the inferior canine issues in direct contact with the last 

 incisor, without the diastema seen in the horse." None of the 

 mandibular symphyses in this collection are well enough preserved 

 to show the unbroken alveolar borders and only show that these 

 two teeth were close together or in contact deep down in the jaw. 

 This is often the case in E. caballus, but the much greater curva- 

 ture of the canine brings it to the surface usually some little dis- 

 tance behind the last incisor, leaving a short diastema. 



It may be added to the description already given by Cope, (i) 

 that the teeth are actually and proportionally much larger, while 

 the bones of the skeleton about equal in size the larger varieties 



