NYCTINOMUS TENUIS. 



extremely rough, being covered with numerous minute warty points, which are 

 individually terminated by a short stiff bristle. 



Of the teeth it is necessary to give a detailed description ; their number is, in the 

 Upper Jaw, 2 front teeth, 2 canine teeth, 10 grinders ; in the 

 Lower Jaw, 4 ditto 2 ditto 10 ditto. 



In the upper jaw the front teeth are large, erect, contiguous, very obsoletely four- 

 sided, slightly convex anteriorly, and concave posteriorly, broad at the base, taperino- 

 towards the point, the side adjoining the neighbouring front tooth, straight ; that 

 directed to the canine tooth, oblique. The canine teeth are greatly lengthened, shghtly 

 bent outward, triangular, with an obscure groove on each side, having the interior edge 

 sharp and cutting, and the base surrounded by a low margin. Of the grinders, the 

 first is very minute, simple, acute, margined at the base, and scarcely projecting 

 beyond the gums. The second, third, fourth, and fifth have a very singular structure : 

 they consist of an elevated exterior margin and a very low interior ridge, between 

 which the crown is very boldly excavated. In the second grinder the exterior margin 

 presents one sharp point, projecting far beyond the other teeth, and passing posteriorly 

 to a very obtuse heel, pressed against the neighbouring tooth ; the interior ridge con- 

 sists of a single attenuated point. The third and fourth grinders are very large, and 

 agree precisely in their structure. The elevated exterior margin is double ; each part 

 consists of three distinct points disposed in a triangle, of which two are exterior and 

 equal, and a third somewhat more projecting, interior ; the lower ridge is emarginate 

 interiorly, and supports two sharp points, of which the anterior is largest ; very 

 bold grooves separate these from the exterior margin. The fifth tooth has, on the 

 whole, the same structure with the third and fourth, but it is smaller, somewhat 

 compressed, and the posterior portion is oblique, and obscurely defined. In the lower 

 jaw, the front teeth are very small, oblique, deeply emarginate, with obtusely rounded 

 points ; the intermediate tooth being largest, and having the interior point somewhat ' 

 lengthened. The canine teeth are long, conical, margined, and greatly enlarged at 

 the base, from which rises an obliquely diverging point directed to the opposite tooth, 

 and forcing the front teeth forward, far from their natural situation. The grinders 

 are compressed, and fitted to the bold excavations of the corresponding teeth in the 

 upper jaw. The first and second are conical, simple, and margined at the base ; 

 the point of the second is somewhat elongated. The third, fourth, and fifth are 

 similarly constructed; each consists of five points, nearly equal in length and 

 dimensions, three of which are anterior, and disposed in a triangle, and two posterior 

 and opposite. The third tooth is somewhat larger than the others, and deviates 

 laterally from the regular series, and the posterior portion of the last grinder tends 

 obliquely outward. 



