MAMMALIA. 
99 
One variety of this species is entirely black, another with a 
white spot on the shoulders, and a third black with white feet. 
Genus 4.—Isodon. — Say. 
Generic Character. —Incisors no canines, grinders ; to¬ 
tal 20. Grinders converging, with flat crowns not divided into 
radicles ; the incisory teeth not narrowed at the top, but obtuse¬ 
ly rounded; fore feet four-toed, with a small tubercle in place 
of a thumb; hind feet four-toed ; the toes in all the feet divided, 
and rest equally on the sole in walking. 
Isodon pilorides. —Known only from the skeleton. 
Genus 5. — Neotoma — Say and Ord. 
Generic Character. —Incisors |, molars^; total 16. The 
incisors in the upper jaw slightly rounded on their anterior face ; 
molars with profound radicles; first molar with five triangles, 
one of which is anterior, two exterior, and two interior; second 
molar with four triangles, one anterior, two on the exterior side, 
and a very small one on the interior side ; third molar with four 
triangles, one anterior, two exterior, and a minute interior one; 
fore feet four-toed, with an armed rudiment of a fifth toe; hind 
feet five-toed. 
Neotoma Floridana — The Florida Neotoma. 
Plate VIII. fig. 5. 
Fur extremely fine, on the upper part of the body lead coloured, 
intermixed with yellow and black hairs ; border of the abdomen 
and throat buff colour ; snout elongated ; whiskers very long; 
eyes and ears very large; tail longer than the body, white be¬ 
neath, dusky above, its scales so small as to be covered with the 
hair. Length of the body seven inches and a half; tail six 
inches and a quarter. Inhabits East Florida. 
Genus 6.— Sigmadon. — Say and Ord. 
Generic Character. —Incisors |, molars ; total 16. Molars 
H 2 
