188 DIPLOPODA. 
RHYSODESMUS. 
Fontaria, Humbert & Saussure, and of subsequent authors ; nec Funtaria, Gray, sensu stricto. 
Rhysodesmus, Cook, Ann. N. York Acad. Sci. ix. p. 5 (1895). 
Characters as above. 
Type, Fontaria limax, Sauss. 
Distribution. North and Central America; ?China and Japan. 
Setting aside the species here described for the first time, all those referred in the 
following pages to the genus Rhysodesmus were assigned by their describers to Mon- 
taria. But this genus, as understood by Saussure and Humbert, Wood, Bollman, and 
others, has of late years been split up into the following genera or subgenera :— 
Fontaria, Gray, in Griffith’s Animal Kingdom, Insecta, 2, xv. p. 787, t. 135. fig. 1 
(1832). Type, virginiensis, Drury, as interpreted by Gray. 
Rhysodesmus, Cook, Ann. N. York Acad. Sci. ix. p. 5 (1895). Type, Fontaria 
limax, Sauss. 
Pachydesmus, Cook, Ann. N. York Acad. Sci. ix. p. 5 (1895). Type, Fontaria 
crassicutis, Wood. 
Eurymerodesmus, Brolemann, Mém. Soc. Zool. France, xiii. p. 101 (1900). Type, 
Fontaria hispidipes, Wood. 
The type of the genus Fontaria is the species represented by the specimens in the 
British Museum identified by Gray with Polydesmus virginiensis, Drury (Ins. Exot. i. 
t. 43. fig. 8, 1770; Westwood’s ed. i. p. 96, t. 43. fig. 8, 1837). These specimens 
differ from all the Central-American examples previously referred to Fontaria in 
having the distal segments of the phallopod strongly arcuate, curved through three- 
fourths of a circle, with the convexity inferior (or posterior), hairy all along its inner 
edge, with the apex strongly expanded and without an auxiliary branch; the basal 
segment rises up into a high shelf-like projection behind the base of the distal 
segment. Moreover, the first segment of the legs, as well as the second, is spined ; 
and the sterna from the tenth backwards are spined, the spines becoming progressively 
stronger in the posterior half of the body. As specific characters may be mentioned 
the coarsely coriaceous sculpturing of the dorsal surface and the equality in length 
between the ultimate and penultimate segments of the legs. 
thysodesmus has been characterized above. The phallopod has a longer or shorter, 
slender auxiliary branch rising from its upper (anterior) side, the principal branch 
being smooth and slender distally with a slightly bifid tip; the basal segment of the 
legs is unspined. 
Pachydesmus is essentially characterized by the structure of the phallopods, which 
have two auxiliary branches—one moderately short, curved, and pointed, the other 
long, as long as the main (or seminal) branch, and apically bifid. The type of the 
genus is Montaria crassicutis, Wood (Proc. Acad. Nat. Sci. Philad. 1864, p. 7; 
