CYCLOTHYROPHORUS. 85 
inferiorly below the level of the third. The remaining segments smooth and shining; the normal 
transverse sulcus complete and preceded by an additional complete sulcus; a well-marked longitudinal 
sulcus in front of and behind the pore. The lateral sulci or striee strongly defined. Anal segment with 
tergal plate obtusely rounded, marked with a transverse rugulose groove ; valves scarcely surpassing the 
tergal plate, strongly punctured, convex and not compressed marginally ; sternal plate rounded. 
¢. Sixth and seventh segments with their lower surfaces thickened and extending inferiorly. Cowxa of second 
leg large; that of third leg bearing a long slender pointed process ; coxe of fourth, fifth, and sixth with 
a wide somewhat triangular apophysis. . 
Number of segments 44. Length 32 millim. 
Hab. Mexico, Cuernavaca. 
This species may be distinguished at once from C. salvini by having the lateral 
portion of the first tergal plate very acutely angled, more strongly emarginate, deeply 
grooved, and extending at least as low as, if not lower than, the second. Also in the 
secondary sexual characters of the male, especially in the processes of the long coxal 
apophysis on the third leg and the marked expansion of the tergal plates around the 
copulatcry apparatus. 
It is possible that the specimens from Cuernavaca referred to C. nietanus by Saussure 
and Humbert in 1872 represent a distinct species, although from the same locality. 
They at least differ from the type in measuring 55 mm. as opposed to 32 mm. in 
length, and in having from 47 to 49 segments instead of 44. 
3. Cyclothyrophorus heteropygus. 
Spirobolus heteropygus, Sauss. et Humb. Rev. et Mag. Zool. 1869, p. 154; Miss. Sci. Mex., Myr. 
pp. 90, 177, t. 4. fig. 22 (1872). 
d+ Blackish, the posterior border of the segments pallid in dried specimens. Mead with 4+5 labral pores ; 
eyes large and circular; antenne tolerably slender. First tergal plate with its infero-lateral portion 
extending as low as that of the second and terminating in a rounded angle, with the anterior border a 
little emarginate and defined by a strong groove; with from 3 to 5 short grooves near its posterior border. 
Remaining segments with their posterior portion punctured, especially in the posterior half of the body ; 
the lateral strize or sulci very strong. Pores large. Anal segment with tergal plate short, rounded 
posteriorly, not surpassing the valves, which are punctured and have their borders neither compressed 
nor sulcate but evenly convex and forming at their junction a re-entering angle. ¢ (immature) with the 
coxe of the legs of the third pair produced into long contiguous processes; those of the fourth to the 
seventh pairs showing a small swelling. Sixth and seventh segments swollen below. 
Number of segments 49. Length 47 millim., width 3°6 millim. 
Hab. Mexico, Cuernavaca. 
This species is said by Saussure and Humbert to be very like S&. nietanus, which 
also came from Cuernavaca, but to differ in having the lateral portions of the first 
tergal plate much less narrowed and emarginate and provided with longitudinal sulci 
near its posterior margin and also in having the inferior sulci much stronger and 
extending up to the pores. It may also be added that the tergal plates are thickly 
punctured dorsally, whereas in S. nietanus they are described as smooth. 
