Systematics of certain Chilognathous Diplopods. 525 
lower grade of evolution in the freedom from the terga of 
the sterna bearing the third to seventh appendages and the 
simpler more archaic construction of the second appendage. 
The female, on the other hand, except in the form of the 
first tergite, is less specialized than the female of Paraiulus, 
the freedom of the sternum of the third leg, the absence of 
genital plates, and the large size of the second legs, all being 
archaic characteristics. In both sexes, as in Paraiulus and 
Lulus, the legs of the first and second pairs belong, I believe, 
to the first and second segments respectively—or, at all 
events, whatever view with regard to the matter be correct, 
no difference is to be found in the three genera mentioned. 
This opinion differs from those put forward by Brélemann 
(Ann. Soc. Ent. Fr. 1902, pp. 440-446) and Humbert and 
de Saussure in 1872, which I believe to be incorrect. 
Brolemann’s criticisms of the view of the Swiss zoologists 
may be accepted as final. He himself gives the leg-formula 
for segments 1 to 6 as follows—O, 1, 1, 1, 2, 2—basing it 
upon the alleged discovery of a limbless sternal plate for the 
first tergite behind the hypostoma of the gnathochilarium 
and in front of the sternal plate bearing the legs of the first 
pair. This sternal plate is of large size and was described 
and figured by Humbert and Saussure. By Silvestri it was 
taken to be the hypostoma; but Brolemann found a trans- 
verse plate between it and the plate he regards as the mentum, 
and this he holds to be the hypostoma. On this point, I 
think, Silvestri was right. The large plate appears to be 
the hypostoma and to be the sternal element of the posterior 
region of the head, to the sides of which it is attached. 
The hypostoma of Brélemann may be a special development 
arising from the chitinization of the membrane between the 
hypostoma and the mentum; or it is possible that the four 
plates of the gnathochilarium in the genus which Brélemann 
names (1) first sternum, (2) hypostoma, (3) mentum, and 
(4) promentum, may be the homologues of the four plates in 
Cambala which Silvestri designates (1) basilar, (2)infrabasilar, 
and (3, 4) the anterior and posterior inframaxillaries (Ann. 
Mus. Genova, xxxvi. p. 51, fig. 14, 1896). In this connexion 
the three transverse plates lying behind the stipites in Para- 
iulus may be suggestively compared with the three figured 
by Cook in his dr: awing of the guathochilarium of the. male 
of Stemmiulus bellus (Amer. Nat, 1895, pl. xh. fig. 1). 
In support of his view Brélemann further alleges the 
dwarfed appendages of the second pair in the female, : at least 
in one of the species examined by him, namely P. ellipticus, 
to be adherent to the vulval sclerites, lodged in the third 
