THE BLACK OR SHIP RAT 589 
slightly shorter than 2; digits 3 and 4 are of about equal length and a 
little longer than digit 2. There are five large and distinct pads, but 
there is no free supplementary pad external to that at the base of 
digit 5. In each foot the hallux reaches to the middle of the first joint 
of digit 2; digit 5 is slightly longer, reaching the end of the first joint 
of digit 4; digits 2,3, and 4 are the longest of the toes, and nearly 
equal to each other, 3 being the longest. There are six plantar 
tubercles ; of these the postero-internal is more than twice as long as 
broad, and it is wider in front than behind; the postero-external pad 
is well developed, and fully one-third of the size of that at the base of 
digit 5; a small free supplementary pad is situated externally but close 
to the pad at the base of digit 5, but no similar pad is normally present in 
connection with the pad at the base of digit 1. Theskin between the pads 
is wrinkled ; elsewhere it is smooth. The tail is long, its length usually 
exceeding that of the head and body; it tapers distally, is somewhat 
square in transverse section and distinctly annulated throughout, there 
being about nine of the scaly rings in a length of 10 mm. near the 
middle; it is clothed with short, stiff hairs both above and below, and 
these rise from the distal edges of the scales. At the root of the tail 
the hairs are sparsely distributed and very short, their length being 
equal to the width of one annulation and a half only; distally they 
gradually become more numerous and longer, their length being equal 
to the width of at least three annulations, and these latter they partially 
or completely conceal. Posteriorly the hairs project slightly beyond 
the tip of the tail, but they do not form a true pencil. The tail is 
relatively longer in the young than in the adult; it is composed of 
thirty-seven or thirty-eight vertebre (de I’Isle), and has from 250 to 
260 annulations in all. There are ten mamme in the females, arranged 
in two pectoral and three inguinal pairs. Occasionally supernumerary 
mamme are developed in the pectoral region; in some cases an 
additional teat may be present externally to either the right or the 
left anterior pectoral mamma; in others an additional pair may be 
developed just in front of or just behind the normal posterior pectoral 
pair. 
Pelage :—The longer whiskers are longer than the head and ears; 
the lower two or three are white, the others dusky. In addition two 
or more long cilia usually rise from the supra-orbital region. 
The general covering of the body consists of three kinds of hairs 
in all rats ; but these kinds intergrade with each other perfectly. Very 
abundant and fine, unicoloured or annulated hairs, which attain a 
length of about 7-5 mm., constitute the underfur. The middle hairs, 
10 to 13 mm. long, are usually annulated, and the general coloration of 
the animal is largely deperident upon the hue of their subterminal 
bands; many of these hairs are coarse and grooved, and impart a 
VOL, II. By 1s PA 
