LITHOBIUS. Ha 
‘Colour ferruginous brown; the last segment of the legs paler. 
“Smaller than L, aztecus; the head with almost the same form, but divided in front by a deep groove, which 
renders it a little bilobate; the frontal sulcus distinct. 
“‘ Antenne longer than in Z. aztecus, more hairy, thinner at the base, composed of from 40 to 46 segments. 
“ Maxillary cove sulcate throughout, with three spiniform teeth on each side. 
“* Hyes small, composed of from 8 to 10 ocelli. 
“‘ Body with its tergites as in L. aztecus. 
“* Anal legs shorter than in L. aztecus, not sulcate below. 
“ Coxal pores round, in a single row, 4, 4,5, 4. Length 18 millim. 
‘*‘ Hab. Mexico, Eastern Cordillera.” 
This description appears to have been drawn up from examples of both sexes, since 
Humbert and de Saussure state that they had five males and three females before them. 
And as they make no mention of variation in the form of the posterior legs in the 
male, it is necessary to conclude that no variation was presented. In which case 
L. mystecus differs materially from all those others described here, which agree with it 
in possessing a large number of antennal segments and a small number of ocelli. 
Fig. 5 on tab. 5 of Humbert and de Saussure’s last great work on the American 
Myriopoda, which is ascribed to L. mystecus, is doubtlessly erroneously named. It 
appears to me to be beyond all question the figure of L. toltecus, the following species ; 
for not only does the figure show the modified anal leg as it is described in L. toltecus, 
but the line which represents the natural size of the specimen, which is magnified in 
the full figure, is of the length not of LZ. mystecus, but of L. toltecus. 
Lithobius toltecus. 
Lithobius toltecus, Humb. & Sauss. Miss. Sci. Mex., Myriop. p. 118 [t. 5. fig. 5]. 
“‘Testaceous. Of small size. The head swollen, divided in front by a deep groove, bilobed between the 
antenne. No frontal sulcus. 
“ Antenne long, composed of 40 or 42 segments. 
“ Maxillary cowe divided by a strong sulcus, not lobate, its anterior border transverse, subangular, but not 
divided, with two spiniform teeth on each side, and sometimes a trace of a third. 
‘‘ Hyes composed of 9 ocelli, arranged in three longitudinal rows, the upper of which is composed of 4, the 
middle of 3, the lowest of 2; the size of the eyes increasing from below upwards, and from before back- 
wards. 
“ Anal legs with fourth and fifth segments [tibia and first tarsal] swollen; the first tarsal dilated, with its 
upper surface bearing a curved projection, which renders the segment bifurcate at its posterior end, the 
internal face bearing a deep elongate depression, from the lower border of which there runs a longitudinal 
row of long hairs. The sixth segment short and lightly swollen. Length 12 millim. 
‘¢ Hab. Mexico, Eastern Cordillera.” 
It appears from this description that L. toltecus resembles L. salvini and L. godmani 
in having the fourteenth pair of legs in the male unmodified, and the tibial and first 
tarsal of the anal legs swollen. But in neither of the two here described as new is 
there any bifurcation of the posterior extremity of the first tarsal segment of the anal 
leg, such as appears to exist in Humbert and de Saussure’s species. 
