Mylodon harlani, from Rock Creek, Texas. 343 



spectively. The latter is somewhat the larger and more robust, 

 but the former yet bears the periotic firmly coossified in posi- 

 tion. The left squamosal I have referred to 10264, but it may 

 have been the opposite of the smaller right one, No. 10265. 



The squamosal resembles that of the JBrea specimen, differ- 

 ing from it mainly in that 'in the latter there is a distinct 

 though low prominence opposite the glenoid fossa which is 

 entirely lacking in the Texas type. This prominence is also 

 present in M. robustus as figured by Lydekker,'* but is less 

 conspicuous in the skull described by Owen. In the Texas 

 form the glenoid fossa is deeply concave transversely, while in 

 the Brea skull it is nearly flat. In No. 10265 there is a distinct 

 circular facet in the fossa which I do not observe in any other 

 specimen or figure. The interior of the bone is extremely 

 cellular, so that the entire anterior limb of the squamosal as 

 preserved is hollow. 



A left jugal referred to No. 10264 is present, though lacking 

 in the fine California skull. Anteriorly the bone is almost 

 complete, showing a large part of the articular surface which 

 must have had somewhat the same area as that indicated in the 

 Brea skull. The bone resembles quite closely that figured by 

 Allen f as Mylodon garmani, but is more slender than in 

 M. robustus. The superior margin of the bone is more 

 abruptly curved than in M. robustus and a marked though 

 obtuse angle limits the inferior margin of the orbit. This 

 angle is represented in robustus by a gentle curve. 



Palate. — The fused palatines and portions of the maxillae 

 are present, to which I have arbitrarily given the number 

 10264, though this reference is incapable of proof. The bone 

 is very massive, which accounts in part for its preservation. 

 Seen from the ventral aspect, it is extremely rugose, and while 

 resembling that of the Brea skull in size, is from an 

 older animal, as the median suture is completely obliterated. 

 The Brea palate is characterized by a delicate median and two 

 lateral ridges, the latter being separated from the alveolar margin 

 on either side by an irregular longitudinal sulcus. In the 

 Texas form these ridges are more pronounced, but the lateral 

 sulci are not distinguishable. In this respect the palate under 

 description resembles more nearly that of M. robustus, especi- 

 ally the so-called male skull figured by Lydekker.J 



The Texan palate shows upon the right side the inner walls 

 of the third and fourth and a portion of the fifth dental alveoli, 

 while, on the left, part of the second is also present. These 



*Lydekker, R., Anales del Museo de La Plata, Paleontologia Argentina, 

 iii, pi. 49, 1894. 



f Allen, G. M., op. cit., pi. 3, fig. 7. 

 % Lydekker, op. cit., pi. 49, fig. 1. 



Am. Jour. Sci.— Fourth Series, Vol. XXXIX, No. 232.— April, 1915. 

 23 



