( 537 ) 



Tht' auus is situated betweeu b iuul b'. When the abdomen is viewed from below, 

 PI. XVII. f. 11), two portions only are visible, the basal portion marked fa') 

 and the larger apical plate (b'), besides the two processes (c). 



As I have previously stated, I am not at present ])repared to describe the 

 Iiomology of the plates marked a, a', b, and b' on PI. XVII. f. 17. Is. lu. It is 

 tempting to snppose that they ro]jreseut the ninth and tenth segments, but this 

 conclnsiou is, I think, not correct ; for in the male the sensory plate is part of 

 the ninth tergite, and it is not impossible that the processes c of the female are 

 homologous to the tenth segment of the male. 



In the male of T. a()i/rte>i the sternite of the eighth segment is very much 

 enlarged and conceals to a great e.xteut the niutli segment (PI. XV.\. f. 1). It is a 

 large concave piece of chitin, sinuate in the mesial line, forming a large cavity which 

 opens dorsally and apically. The bristles of tlie eighth sternite are characteristic 

 of each species. They differ in number and position in each species of Tyj>Idopsylla. 

 The eighth tergite is rather small, and is of a singular appearance, in consequence 

 of the peculiar development of the stigmata. A dorsal view of this portion is 

 given on PI. XVII. f. 14. The two stigmata are not simple circular openings. 

 They are much dilated along the edge of the segment, both dorsally and ventrally. 

 and meet in the middle line, where the segment is deeply sinuate. The sinns, 

 which docs not reach halfway across the segment, forms part of the stigma-cavity, 

 which is densely clothed with fine hairs. The development of the eighth segment 

 in the male as here described seems to be peculiar to the genus Ti/phlojiSylla. 

 The genera Ceratojw/lla, Ptilex, and . Ceratopl'i/llus have a very small eighth 

 sternite, consisting of two separate narrow plates (PI. XVI. f. Id. viii. v). 

 The eighth tergite in these genera is very large. In Ceratopsylla elowjatax 6 

 (PI. XVI. f. 10) the eighth tergite is divided dorsally in the middle : each 

 plate thus formed is sinuate. The sinus sej^arates from the plate a lobe which 

 protrudes dorsad. At the base of the lobe the comparatively small stigma is 

 placed. The sexes of Cerutophyllus, Pulex, and Ceratopsj/lla agree with one 

 another with regard to the relative size of the sternite and tergite of the eighth 

 segment. In this respect these genera dirt'er markedly from T>/plilops>jlla. 



If the eighth sternite and also the lower part of the eighth tergite of Typhlo- 

 psylla agyrtes be removed, the copulatory apparatus of the male and the pygidiimu 

 are seen. PI. XVII. f. iL'. 14 represents them in situ. Betweeu the eighth 

 tergite (PI. XVll. f. 12. viii. dj and what is distinguished as x in the same 

 figure the sensual plate is situated. The lateral portion of ix. d, which is 

 separated from the dorsal portion by a dee]i sinus, is again divided into two 

 processes p and p', and produced internad into a long curved process on each side, the 

 manubrium of Wagner. The dorsal and lateral portion of ix. d form one plate, 

 tlie ninth tergite, moveable only in toto. Dr. Wagner has figured this apparatus 

 as here described (piite correctly, and I repeat it only for the sake of completeness. 

 Joined to the large and complicated ninth tergite is a boomerang-sbajied organ 

 (PI. XVII. f. 12. ix. V) which is provided with hairs at the apex in a 

 characteristic way. Another moveable j)iece of chitin is also joined to ix. d, 

 iiamely the organ f, whicli lies at the inner and ventral side of the process p'. The 

 hairs upon the moveable " finger " f are connected with the interior of the organ, 

 which is hollow, and seem to be sensory hairs. Jnst behind the dorsal sensual 

 plate there is a transverse snture which separates the anal convex plate x from 

 ix. d. This suture is alsn iiluiniy \ isilih', when vieweil iVom above (PI. XVll. 



