COLOBODESMUS. 129 
of those organs. So far as was known to Brélemann, the phallopod of Sphwriodesmus, 
apart from the basal segment, consisted of an elongated tibio-femoral segment. with or 
Without accessory branches and processes, but with the seminal duct opening upon the 
seminal style situated at or near the apex of the organ. But in Colobodesmus the large 
and stout femoral segment is followed by a very short subannuliform tibial segment, 
bearing a short and conical process upon which the seminal duct opens. Beyond this 
the tibia is produced into two relatively very large, somewhat lamellar, but irregularly 
shaped plates projecting far in advance of the orifice of the seminal duct, which is thus 
remote from the distal end of the phallopod. 
Brodlemann adds to his diagnosis of this genus the remark that the species described 
as S. gracilis by Saussure and Humbert appears to belong to Colobodesmus. If so, 
Colobodesmus is a synonym of Cylionus. On the other hand, there cannot be much 
doubt that C. gracilis and C. constrictus are congeneric ; and the very considerable 
similarity that the phallopod of C. constrictus presents to the phallopod of Cyclodesmus 
aztecus (in which the seminal duct opens, according to Carl, just behind the tip 
of that organ) points to the existence of the same difference between Cylionus and 
Colobodesmus as between Colobodesmus and Spheriodesmus with respect to the termina- 
tion of the seminal duct. 
In the new species of Spheriodesmus described in the preceding pages I have not 
traced the course of the seminal duct and the position of its orifice. But the discovery 
of some of these species, notably of S. prehensor, shows that the structure of the 
phallopods is far more variable than Brélemann supposed. Nevertheless the structure 
of this organ suggests in all cases that the orifice of the seminal duct is subterminal. 
Even in S. rolustus there seems to be a distinct seminal style in the hollow of the 
shovel-shaped termination of the phallopod.  Brélemann unfortunately does not 
describe in Colobodesmus the shape of the posterior borders of the inferior surface 
of the segments, so that it is unknown whether his genus approaches Spheriodesmus 
or Cylionus, or is unlike both in this respect. 
1. Colobodesmus biolleyi, Brél. 
Colobodesmus biolley?, Brdlemann, Aun. Soc. Ent. Fr. Ixxiv. p. 350, t. 8. figg. 8-12, t. 9. 
figg. 13, 14 (1905) *. 
From the long description of this species it is difficult to pick out definite specific features apart from those 
belonging to the male sex. Brélemann says, however, that the anterior and posterior borders of the keel 
of the fourth segment are parallel, a statement which suggests that they are straight in a vertical line, and 
not convex and concave as in all the species of Spheriodesmus and Cylionus. If they are curved in 
those genera they are not, strictly speaking, parallel. It also appears that the posterior angle of the 
keel is not in any sense produced, although acute. The first leg of the male has a large tuberculiform 
tooth on the base of the femur, and the latter segment is concave below, convex above. The socket of 
the phallopods is wide, as is also the sternal area between the posterior legs of the seventh segment, 
Length (?), width up to 8-5 millim. 
Hab. Costa Rica, San José, Caché (Biolley 1), Cariblanco (Lankester '). 
BIOL. CENTR.-AMER., Diplop., October 1909. g 
