NEOLEPTODESMUS. 181 
The above-given characters have been taken from the descriptions published by 
Saussure and Carl. Saussure refers to a large male example discovered on the Volcan 
de Orizaba, and the discrepancy in size between the length of the male and female 
measured suggests that the dimensions of the male were taken from this example. 
The latter, however, was probably a representative of a species distinct from the 
females if the measurement is correctly printed. 
2. Neoleptodesmus sumichrasti. 
Polydesmus (Oxyurus) sumichrasti, Humb. & Sauss. Rev. et Mag. Zool. (2) xxi. p. 151 (1869)’; 
Miss. Sci. Mex., Myr. p. 49, t. 1. fig. 8 (1872) *. 
Polydesmus (Oxyurus) tatermedius, Humb. & Sauss. Rev. et Mag. Zool. (2) xxi. p. 151 (1869)? ; 
Miss. Sci. Mex., Myr. p. 49, t. 1. fig. 10 (1872) * (ex Carl). 
Neoleptodesmus sumichrasti, Carl, Rev. Suisse Zool. xi. p. 558 (1903) °*. 
Colour whitish. Very nearly allied to W. ortzabe, but with the dorsal surface flatter. eels tolerably wide, 
transverse, with rounded angles, the posterior angle not obliquely cut away nor hollowed behind the 
swelling carrying the pore, the thickening of the margin continued right round the edge, and not 
exhibiting any button-shaped excrescence such as is seen in NV. aztecus; keels of 17th and 18th segments 
with posterior angle prolonged behind; those of the 19th simply spiniform. Keels of the 1st tergal plate 
very long antero-posteriorly, and rounded marginally. Caudal process of anal segment with edges less 
sinuous than in NV. orzzabe, Sides of anterior segments rugulose, granular at the anterior end of the body. 
Phallopods very like those of NV. aztecus, but with the distal segment much less arcuate, the median 
branch lightly concavo-convex, much less dilated than in .V. aztecus, with the apex truncate and 
emarginate, the inner of the two subsidiary branches with straight subserrate upper edge, the outer 
simply pointed and not wide as in NV. aztecus. 
Length 30 millim., width 3°6. 
Hab. Mexico, Orizaba (Swmichrast 1°). 
8, Neoleptodesmus orizabe. 
Polydesmus (Oxyurus) orizube, Humb. & Sauss. Rev. et Mag. Zool. (2) xxi. p. 151 (1859)'; 
Miss. Sci. Mex., Myr. p. 48, t. 1. figg. 11, 11 @ (1872) *. 
Q. Closely resembling N. aztecus. Colour whitish. Body smooth, cylindrical, attenuated posteriorly, eels 
very small and widely separated, arcuate in front and subangular behind; the caudal process of the 
anal segment with its sides very markediy sinuous. 
Length 35 millim., width 8 (? misprint for 3). 
Hab. Mexico, Orizaba 1 2, 
The generic position of this species is doubtful, the male characters being unknown. 
According to Humbert and Saussure the female may be distinguished from that of 
N. aztecus by the sinuous edges of the caudal process, by the posterior extremity of 
the body being more attenuated, the entire body thinner, the back flatter, the keels 
narrower, with the anterior segments more regularly vaulted owing to the keels being 
more sloping. 
It may be noted that although these authors state that the body is narrower in this 
