No. i.] Allen on Mexican Mammals. 193 



Duenas. These two specimens are apparently all thus far referred 

 to L. palustris from Mexico or Central America, or from any point 

 outside of the lowlands of the coast region of South Carolina and 

 Georgia, and the peninsula of Florida. 



In now describing this new form, it gives me pleasure to name 

 it in honor of the Curator of Mammals at the U. S. National 

 Museum, to whose kind offices I have been many times indebted. 



Similar to L. palustris in all external characters, except that it is rather darker 

 in color, and much more varied with black above, which is almost the prevailing 

 tint over much of the dorsal region. Feet quite as scantily furred as in L. 

 palustris. The skin is unfilled, and hence satisfactory measurements cannot 

 be taken. (The feet have been partially denuded by insects.) It is evidently 

 smaller than average full grown specimens of L. palustris. Length of hind 

 foot, 75 mm. ; of fore foot, 40 ; height of ear from crown, 54 ; from notch, 46. 



Cranial Characters. The skull is imperfect, lacking most of the occipital 

 portions. It shows the animal to have been fully adult. In dorsal outline it 

 much resembles skulls of L. sylvaticus aztecus, except that the cranial portion 

 is more depressed posteriorly ; the frontal and parietal bones much pitted, as 

 in L. palustris and L. aquaticus. The postorbital processes are slender, and 

 barely touch the cranium posteriorly, thus enclosing a large broadly oval foramen. 

 The zygoma is broad and short, flattened below anteriorly and not much ex- 

 panded, with the sinus on the lateral face anteriorly about as in L. sylvaticus. 

 The zygomatic and mastoid portions are vertically much expanded, the zygoma 

 being thus much shorter and relatively much broader than in any of the allied 

 forms ; with a length of 28 mm. the vertical breadth is 4.5, against 30 and 4 

 respectively in L. sylvat^c^^s aztecus, and 34 and 3.5 in L. palustris of corre- 

 sponding general size. The teeth are broad, the middle upper molars having a 

 transverse breadth at the crown surface of 4 mm. against a total length of the 

 upper molar series of 12. The palatal region is very broad (distance between 

 inner base of middle molars 12.5), with a very short palatal bridge (6 mm.) ; 

 there is a slender spiny process on the anterior border, with, however, no trace 

 of any on the posterior border. The palatal walls are widely separated, forming 

 a broad U-shaped arch instead of the narrower and more sharply V-shaped arch 

 of L. palustris and other allied forms. The basisphenoid stands at about the 

 usual angle with the axis of the skull, and the basioccipital lies in the same plane, 

 instead of forming, as in allied species, an obtuse angle with the basisphenoid. 

 The nasal bones are much flattened and much less than half as much arched in 

 front as in any allied form. The posterior half of the brain-case is very abruptly 

 depressed, in conformity to the depressed plane of the basioccipital below. The 

 middle portion of the skull is very broad in comparison with the width of the 

 brain-case, or with the total length of the skull. 



The following are the principal measurements : Basilar length, 57 mm. ; total 

 length (?) ; greatest breadth (at zygomatic arch), 35 ; least interorbital breadth, 



