PLATYDESMUS. 47 
as to conceal it partially from above; this border is somewhat deeply notched in the middle line and on 
each side of the notch it diverges obliquely outwards and forwards, being slightly convex. The granules 
of the posterior row on the terga extend farther on to the keels, being more numerous than in P. hirudo 
and about a dozen in number. Sterna of the mid-region of the body wider than in P. hirudo, their 
transverse length being about equal to the length of the coxa and trochanter of the leg. 
Total length, ¢, 20, width 5 millim.; 9, 23, width 5 millim. 
Hab. Mexico, Omilteme in Guerrero (/. H. Smith). 
6. Platydesmus marmoreuws, sp.n. (Tab. V. fig. 3.) 
Colour : head fuscous above, paler below; tergal plates dark yellowish brown, turning to paler yellow on the 
keels ; in the dorsal middle line a pale stripe which expands in its course into four triangular patches, 
and on each side immediately behind the posterior angle of each patch there is a pair of conspicuous 
yellow spots lying towards the base of two of the keels; last tergal plate yellow; antenne, legs, and 
sterna yellow. 
Body rather wide, about four times as long as broad (14:34). Head with distinct eyes. First tergal plate 
covering the head, its anterior border developed into a right and left lamina with convex inner angles 
and separated by a short acutely triangular notch ; the anterior row of tubercles on this tergite lying 
nearly midway between its posterior and anterior borders. On the remaining segments the anterior row 
of tubercles extending along the middle of the keels, the posterior row stopping short at their base. Last 
tergal plate narrowly piriform, sublanceolate, much narrower than the keels of the preceding segment, 
which overlap it largely posteriorly and nearly meet in the middle line behind its apex. Sterna of the 
mid-region of the body wide, their width about equal to the length of the two basal segments of the legs. 
Number of segments 43. 
Total length 14, width 33 millim. 
Hab. Guatemata, Cholhuitz (Stol/). 
This species has considerably larger lamine on the first tergal plate than P. meso- 
melas, and further differs in colour. In the latter respect P. marmoreus approaches 
P. triangulifer. 
7. Platydesmus perpictus, sp. n. (Tab. IV. figg. 1, 1 a-/.) 
Colour marbled ; middle of dorsal area a rich dark brown extending to the base of the keels, but interrupted 
at tolerably regular intervals on each side of the middle line by conspicuous yellow patches, about nine 
in number, composed of spots of that colour upon two or three consecutive segments; keels mostly 
yellow, but those opposite the intervals between the yellow patches suffused with brown extending from 
the median portion of the segments, but often separated therefrom by indistinct paler spots; last tergal 
plate infuscate ; head infuscate above; antenne, legs, and ventral surface pale. 
Body wide, about four times as long as broad. Head with eyes ; completely covered. rst tergal plate with 
its anterior border produced into a pair of large lamin, separated from each other in the middle line by 
a narrow longitudinal space. The two rows of tubercles on the segments extending nearly to the 
extremities of the keels. Last tergal plate narrowly oval, far surpassed posteriorly by the keels of the 
preceding segment. Sterna of the mid-region of the body very broad, wider than the two basal segments 
of adjacent legs, and about four times as broad as the length of the coxa. Number of segments in adult 
47-65, more or less. . 
Total length of type 25, width 6°8 millim. ; of a large specimen 30, with a width of 7-5 millim, 
Hab. Guatema.a, Senahu (Champion), Cholhuitz (Stol0). 
There is also in the British Museum a specimen of apparently the same species 
from Belize, British Honduras. . 
