178 



The specimen (fig. 20, a) shows two molars and four premolars ; the incisor is neither 

 chisel-shaped nor procumbent, but rises with a slight curve to its pointed apex at an 

 angle of 120°, with the line of the molar alveoli. The length of the dental series from 

 the apex of the laniariform incisor to the hind part of the second molar is seven-six- 

 teenths of an English inch, precisely the length of the dental series in Urotrichus tal- 

 poides (ib. b), a ferine mammal, 5 inches long from the snout to the tip of the tail, with 

 a skull 1 inch in length, and an approximate pair of lower pointed incisors upcurved at 

 the same angle to the molar line as in Plagiaulax minor, but relatively less and shorter. 



Some Opossums, e. g. the murine and dorsigerous Philanders (fig. 20, c)*, have 

 the mandible intermediate in size between that in Plagiaulax minor (a) and in Plagi- 

 aulax PecMesii (f) ; it is both shorter and weaker than in the latter species. A natu- 

 ralist and good observer (Dr. Cakter Blake, F.G.S.) has expressed to me his surprise at 

 witnessing, while in Central America, the disproportion of size between those mouse-like 

 predaceous Marsupials, and the Lizards and Snakes on which they prey. 



Fig. 20. 



Plagiaulax minor. 



Urotrichus talpo'ides. 



Didelphis murina. 

 fc^^g^aAaa ^ Mustela vulgaris. 



Plagiaulax Falconeri. 



Plagiaulax Becklesii. 



Potamogale velox. 



The above figures of the mandible and mandibular teeth are of the natural size. 



1 am not cognizant of any grounds afforded by zoology whieh forbid the supposition 

 that a mammal of five inches in length, with the carnivorous type of dentition of Plagi- 

 "ii lax, may have been able to capture and kill the diminutive Lizards (Saurillus, Ma- 

 * In D. dorsigera, from tip of incisors to condyles, 10 lines; in D. murina \ \\ lines. 



