Plague / Its Cause and the Manner of its Extension, Its Menace, Its Control and Suppression, Its Diagnosis and Treatment

by Thomas Wright Jackson

In the Philippine Islands no specimens of Gunomys have been observed, but M. rattus and M. decumanus are both present and numerous and both are subject to plague, as shown by the presence of the disease in specimens examined.

In view of the unreliability of the points of difference in rats usually given as identifying data, such as the number and location of the mammæ, the variations in color and the peculiarities of the footpads, the Javan observers depend upon the conformation of the skulls for the determination of genera, the skull of M. rattus being oval and arched, that of M. decumanus more closely approaching the square and rectangular conformation, and that of Gunomys being broader, higher and longer than either.

In M. rattus the prominent borders which separate the parietal from the frontal surfaces of the skull are oval; in M. decumanus they are parallel or slightly divergent; in Gunomys they are lyre-shaped.

M. rattus

M. decumanus

Gunomys

To determine these differences the heads of the rats are cut off, the tissues desiccated by antiformin, or by boiling and stripping.