388 DR. K. JORDAX AND HOX. N. 0. ROTHSCHILD OX 



7 bristles, and near these bristles about 8 more, of whicli 2 are 

 long (text-fig. 120). In hidentatiformis the marginal row contains 

 9 bristles and there are about 15 lateral ones, of which at least 

 4 are long. In both species is the head of the receptacukim seminis 

 half as long again as broad, and the tail half as long again as the 

 head. The two insects do not present any appreciable difierence 

 in this organ. 



One female from Yu-lin-fu, Shensi, 4000 ft., taken off Dignus 

 sotiierhyi. 



12. ISTeopsylla aliena, sp. n. (Text-figs. 121, 122.) 



(5 5 . Differs from true Neopsylla in the hind coxa bearing a 

 patch of short spines on the inner surface, and in the fiftli segment 

 bearing in all the ta,i'si five lateral bristles. Both chai'acters are 

 of great interest. The development of bristles into short spines 

 on the hind coxa is met with in many genera of fleas, but not in 

 Ceratophyllas proper, not in JVeopsi/Ua, Ctenojihthalmus, and FalcHO- 

 psylla^ except the two new Neopsylla here desciibed. A survey 

 of the genera which bear coxal spines renders it evident that such 

 spines have been acquired independently in many instances and do 

 not necessarily indicate close affinity. A species with spines may 

 be more nearly related to one without them than to another which 

 also bears coxal spines. 



Five lateral bristles on the fifth tarsal segments are an ancestral 

 character for fleas, the segment with more than five such bristles, 

 or with the proximal pair shifted on to the ventral surface, or with 

 less than five pairs being more recent modifications. The five 

 pairs are normal for Ceratophyllus, while the species of Neopsylla, 

 ralceo23sylla, Gtenoplithalmus, and Amplupsylla have either five 

 pairs in the hind tarsus with the first pair placed in between the 

 second, or possess only four pairs. The jDvesent new species, there- 

 fore, connects that group of genera with normal t'eratophyllus. 

 But the interest of the species does not end there. We find that 

 the fifth tarsal segment of one hind leg has in both our females 

 on one side fovu^ and on the other five bristles, while the segment 

 has five on both sides in the other hind leg. In two of three 

 males, both hind legs have five bristles on both sides of the fifth 

 tarsal segment, whereas in a third male this segment has only four' 

 pairs of bristles. In all three instances where the number of 

 bristles is reduced, it is the proximal pair, or a bristle of the 

 proximal pair, which is absent. This appears to be decisive evi- 

 dence that also in the allied species which have only four pairs of 

 lateral bristles on the fifth hind-tarsal segment it is the first pair 

 which has been lost. 



Head. — Evenly rounded, the frontal outline vertical in the S , 

 more slanting in the 5 . Eye indicated by a narrow oblique bar. 

 Two genal spines, which cross each other as in many of the species 

 of this relationship, the outer spine being short and broad and the 

 lower one long and pointed. The genal lobe itself is narrower at 

 its base than in the centre, being sole-shaped. The frontal 



