Art. 24 TEXAN PLEISTOCENE VERTEBRATES HAY 5 



Two fragments of the carapace found at Sinton were presented by 

 Doctor Francis to the United States National Museum. To these 

 are assigned the number 11,379. 



Since going to press Doctor Francis has sent a photograph of 

 another fragment of the carapace, which presents 11 rosettes and 

 three bones along the border. So far as can be determined these 

 appear to be similar to those of some part of the border of the speci- 

 men found at Wolfe City. 



NEOCHOERUS PINCKNEYI (Hay) 



Plate 1. tig. 2: plate (J, tig. 2; plate 7. fig. 2 



In Doctor Francis' collection are found a part of an upper jaw 

 and a part of the left side of a lower jaw of a species of rodent 

 related to the South American capybara. The lower jaw presents 

 the premolar, the outer walls of the sockets of the two anterior 

 molars, and a small part of that of the last molar, also the outer 

 wall of the socket of the left incisor. The whole fragment is 122 mm. 

 long. The three anterior teeth occupied 80 mm. of the jaw, and 

 the whole tooth line was close to 108 mm.; that of a specimen of 

 Hydrochoerus hydrocJioer^s at hand is 79 mm. long. The premolar 

 appears to differ from that of the existing capybara only in size. 

 Its length is 29 mm. on the outer border; the oblique width at the 

 rear is close to 13 mm. 



Some important differences between this jaw and that of the 

 South American capybara are noted. In the latter there is on the 

 outer face of the bone a broad shelf, the masseteric ridge, which 

 furnishes attachment for the various divisions of the masseter mus- 

 cle. In the existing capybara the ridge begins at the condyloid 

 process and, expanding in its course, forms a rounded prominence 

 beneath the premolar and subsides below the front of this tooth. 

 In the fossil jaw (pi. 1, fig. 2) the ridge doubtless originates at the 

 condyloid process and, pursuing its way, develops its prominence 

 not quite so far forward as in the capybara, and the ridge subsides 

 below the middle of the mohir. As a result the front of the jaw was 

 not so suddenly narrowed as it is in the capybara. The course of 

 the shelf is not so straight as in the capybara, its upper border 

 being considerably arched, and the anterior end of the muscular in- 

 sertion is curved downward. The shelf is 14 mm. thick below the 

 third tooth; only 8 mm. in the capybara. 



In the capybara the coronoid process is thin and prominent, curv- 

 ing outward and upward and rising some 13 mm. above the alve- 

 olar Ijorder. In the fossil (j)!. 8, fig. 2) it does not reach the level of 

 the alveolar border, but extends somewliat outward and backAvard 

 as merely a continuation of a ridge just below the tooth row. The 

 incisor tooth was relativelv larger than it is in the capybara, its 



