14 The Non-Combed Eyed Siphonaptera 
the pronotum possibly has secondarily become longer than it originally 
was. 
Pariodontis exhibits the extreme development as regards the 
extension of the tergites of the thorax, while the Sarcopsyllidae, on the 
other hand, have the tergites of the thorax reduced to narrow strips, 
P. irritans and L. cheopis (and allies) representing intermediate phyletic 
stages. 
The Sarcopsyllidae, though differing so markedly from Pariodontis in 
the development of the tergites of the thorax, have a character which 
is not found in Pulex and its other near allies, but is present in the 
porcupine flea, this being the curved tooth (projecting back- and down¬ 
wards) into which the lower oral corner of the mouth is prolonged. 
This hook is present in all the Sarcopsyllidae, but in the other families 
is absent, except in the genera Pariodontis, Moeopsylla and Lycopsylla. 
This character has probably been acquired independently in these different 
genera, serving the same purpose as the genal comb of other fleas, 
namely, to prevent hairs getting into the joint between the head and 
the prosternite when the parasite is passing through the fur of its host. 
In other respects P. riggenbachi is closely allied to the genus Pulex, as 
well as to Loemopsylla, but resembles Loemopsylla in the structure of 
the male genitalia. The male genitalia of Pariodontis in fact show the 
same specialised form as in Loemopsylla and differ markedly from the 
male genitalia of P. irritans. 
(1) Pariodontis riggenbachi Rothsch. (1904). 
(PI. II, fig. 1.) 
£ $, Pulex riggenbachi Rothschild (1904, p. 611, n. 7, t. 8, figs. 19, 20, t. 9, fig. 24, 
Cape Colony and Morocco, name-type from Cape Colony). 
The first specimens of this large species were sent to us by 
W. Riggenbach, who collected them off Hystrix cristatus in Morocco in 
1900. Since then we have received the insect from other parts of 
Africa also, the host being in every instance the same. 
Mogador, Morocco, November 1904, and Mazagan, Morocco, collected 
by W. Riggenbach. 
Deelfontein, Cape Colony, July 1902 ; C. H. B. Grant. 
Mangona R., Bihe, Angola, January 1904; Dr W. J. Ansorge. 
