PLATYDESMUS. 
6’. Anterior border of first tergal plate widely emarginate, without 
any forwardly directed laminate expansion, anterior edge of 
the body of the segment uncovered in the middle line; head 
completely exposed. 
a’. Evenly longitudinally banded above, the keels yellow, a 
narrow pale median dorsal stripe, the area between this 
stripe and the base of the keels uniformly black. 
a’, Broader; sternal areas of segments in mid-region of 
body wider than length of two basal segments (excl. 
trochanter) of legs. . . . . < see ew 
6°. Narrower; sternal areas of segments narrower than 
length of two basal segments (excl. trochanter) 
6°’. Pattern variegated, not consisting of evenly alternating 
bands of black and yellow, median dorsal stripe broken 
up, keels not uniformly yellow. 
a". Body wide, only about four times as long as broad; 
keels with one row of granules. . . . .. , 
6". Body narrow, at least six times as long as wide, both 
anterior and posterior row of granules extending almost 
to the extremity of the keels. 
a*. Median dorsal band broken up into definite elongate 
triangular patches; anal tergum smaller; keels less 
granular ., . . er ‘ 
6°. Median dorsal band n not broken up into ) definite trian- 
gular patches ; anal tergum larger, subquadrate; keels 
with granules in addition to those of the two normal 
YOWS . 2. 6 6 ew ew ew wee ee 
45 
hirudo, sp. n. 
lineatus, sp. n. 
mexicanus, H. & S. 
triangulifer, sp. n. 
analis, sp. n. 
1. Platydesmus triangulifer, sp. n. (Tab. IV. figg. 4, 4 a-e.) 
Colour: dorsal area of segments blackish with pale median band, which is not of even thickness throughout 
but is broken up at fairly regular intervals into six elongate triangular expansions, being broadest upon 
the sixth, fifteenth, twenty-fourth, thirty-fourth, forty-fifth, and fifty-second segments; where the 
expansion occurs the black is reduced in width and intensity, and slightly diverges from the middle line; 
keel and lateral area of dorsal region of segments yellowish-brown, but the segments on which the median 
dorsal pale stripe is narrow ornamented with a much more clearly defined yellow spot between the 
median line and the base of the keel ; last tergal plate yellowish-brown ; head infuscate above, antenne 
and legs yellowish. 
Body moderately long and slender, about six times as long as broad (21: 3:5). Head with eyes. First tergite 
widely emarginate in front; the thickened anterior rims of the lateral keels widely separated in the 
middle line. T'ubercles on segments strong, those of posterior line about thirteen in number on each 
side, and extending right on to the keels. Last tergite relatively wide, but narrowed posteriorly, and 
surpassed by the keels of the preceding segment. Sterna of mid-region of body nearly or about as wide 
as basal segments of appendages. Number of segments 56-58. 
Total length 21, width 3°5 millim. 
Hab, Guatemala, Volcan de Acatenango (Sfol/). 
