196 DIPLOPODA. 
crossing; when viewed from the side the principal (seminal) branch shows a slight upward curvature, 
separated from the auxiliary branch by a wide suboval space, the branch short, slender, inclined obiiquely 
upwards, then forwards. 
Length of ¢ 36 millim., width 7°5; length of antenna 6°5 millim. 
Hab. Muxico, temperate regions of the plateau at localities ranging from 1000 to 
8000 feet in altitude—Mirador, Cordova, and the plateau of Anahuac round Puebla 
and Chalchicomula (Saussure !?), Peak of Orizaba (Mus. Brit.). 
The specimen above described as &. montezume is one from the Volcan de Orizaba 
in the British Museum. Apart from its decolorization, it agrees very well with 
Saussure’s figures and description of that species. 
According to him, the normal colour is chocolate-brown, with the anterior border of 
the first tergal plate and at least the angle of the keels of the rest, and sometimes the 
posterior border of the median area of the segments, red or yellow ; the lower side of 
the body is also yellowish or reddish, like the two dorsal segments of the legs. In size 
Saussure’s specimens varied from 37 to 42 millim. in length and from 8 to 9 in width. 
The specimen ticketed ‘‘ North America” (Senckenberg Museum), and described by 
Attems as Fontaria montezume, differs from all the Central-American species of the 
genus Rhysodesmus that I have seen in having a small spine upon the basal segment 
of the legs. What this species may be I do not know; but it is certainly different in 
the character mentioned from the example I have identified as &. montezume. In all 
probability it did not come from Central America. 
2. Rhysodesmus totanacus, (Tab. XIV. figg. 8, 8a.) 
Polydesmus (Fontaria) totanacus, Sauss. Linn. Ent. xiii. p. 821 (¢) (1859)'; Mém. Soc. Phys. 
Genéve, xv. p. 322, t. 2. fig. 14 (1860) °*. 
3. Colour (in alcohol) greyish-olive above, the keels a little paler, a large dark spot close to the base of each 
keel in front, the two connected by a dark stripe running transversely along the groove between the 
zonites ; a corresponding recurved mark upon the first tergal plate ; prozonites dorsally pale, laterally 
darker; head and antenne brown, the antenne distally infuscate; sterna and legs pale. Antenne 
about as long as the width of the first tergal plate, shorter than that of the second and succeeding 
segments back to the 17th; segments 2 to 5 equal to width of head. First tergal plate narrower than 
2nd; its anterior border not quite evenly convex; its lateral third on each side obliquely cut away, 
the lateral angle subacute, posterior angle of 2nd and 38rd rounded; metazonite of 2nd not 
markedly shorter than the keel. Aceels of 2nd, 3rd, and 4th lightly depressed, of. the following 
segments becoming gradually more and more horizontal, though upraised posteriorly ; those of the 18th 
the most nearly horizontal of the series. Dorsal surface convex, very lightly coriaceous, becoming more 
coarsely so towards the base of the keels, which are wrinkled above and subgranular ; the groove well 
marked and striate, not continuous with the groove defining the anterior edge of the keels; this edge 
convex, the groove markedly sinuous, with the forward curvature some distance from the angle which is 
convex ; the lateral margin of the keel nearly evenly thickened throughout its length; the pores situated 
well forwards—in front of the middle of the metazonites on the anterior and middle segments, in a line 
with the posterior border on the 18th; posterior angle of keels not produced; from the 4th to about 
the 9th obtuse, from the 11th to the 16th subrectangular, from the 17th to the 19th produced but 
rounded, those of the 19th well developed and projecting well beyond those of the 18th; posterior border 
of the keels markedly convex, strongly so close to the metazonite, and from the 4th to the 10th 
