SPIROBOLID. 89 
The Central-American genera of Spirobolide admitted in the preceding pages may 
be distinguished as follows :— 
a. Labral setal pores 2+2 on each side; first tergal plate widely 
rounded laterally and not extending inferiorly so low as the 
infero-lateral portions of the second; a pair of impressions 
followed by a striated area (scobinz) present close to the 
anterior border of more or fewer of the tergal plates; sternal 
plate of copulatory apparatus very large, linguiform, sub- 
triangular, its median portion projecting inferiorly as low or 
almost as low as the anterior laminz of the coleopods ; 
phallopod slender, two-jointed, the terminal segment ending 
in a slender seminal style and a broader guard. 
b. Summits of anal valves not produced into spiniform processes. Rurnocricus (p. 59). 
6'. Summits of anal valves produced into spiniform processes . OxypyceE (p. 73). 
a‘. Labral setal pores variable in number, never constantly 2+2 ; 
first tergal plate usually narrowed and triangular, never widely 
rounded ; no scobine; sternal plate of copulatory apparatus 
much smaller, usually narrow and transverse and never ex- 
tending inferiorly in the middle line so low as the inferior 
admedian angles of the anterior lamine of the coleopods ; 
phallopod otherwise formed. 
c. Valves of anal segment bent sharply inwards in their posterior 
portion and forming at their junction a deep groove or re- 
entering angle . . 1. we ew ee ee ee oe). CYCLOTHYROPHORUS (p. 83). 
c'. Valves of anal segmeut not bent sharply inwards posteriorly, 
their margins usually compressed, not forming a re-entering 
angle at their junction. 
d. First tergal plate laterally narrowed, triangular, and not 
extending inferiorly so low as the infero-lateral portion of 
the second ; sternal plate of copulatory apparatus not 
laterally bicornuate dorsally,-but slender and narrow . . Spiropowus (p. 74). 
d'. First tergal plate less narrowed laterally and extending 
inferiorly as low as the infero-lateral portions of the 
second, which is thus concealed; sternal plate of copula~ 
tory apparatus elevated laterally on each side into a stout 
cornuate process... . 1 eee ee he ee) SPIROBCLELLUS [p. 86). 
BIOL. CENTR.-AMER., Diplop., 4pril 1909. N 
