560 Mr. D. Sharp and Mr. F. Muir on the Comparative 



ture on the apes of the internal sac differs in details (PL LXXII 

 figs. 200, 200a). 



D. hidens and D. semicuprea,. 



Aedeagus very like X>. comari, but the armature on the sac is 

 totally different (PI. LXXII I, tigs. 201 and 202). 



B. lemnae. 



Has the cap long and thin. The armature on sac is distinct from 

 those described above (PI. LXXIII fig. 203). 



Carpophagus Imnksiac (PL LXXIII figs. 204, 204«). 



Median lobe large, chitinous, tubular and curved ; the median 

 orifice at apex, the median foramen occupying the ventral basal half. 

 Tegmen forming a ring-piece, with a very long lobe as cap. Internal 

 sac large with complex armature at apex (204a) consisting of a pair 

 of complex side lobes {c) and a slender median process (6) through 

 which the ejaculatory duct passes and opens on its apex. 



Mecynodcra halyi. 



Median lobe well chitinised, curved and fairly short, forming a 

 flattish tulie ; the ventral edge of the median orifice projecting 

 beyond the dorsal edge : median foramen large, occupying the 

 ventral portion of the basal half. Tegmen forming a ring-piece, 

 with large cap apically deeply divided and furcate ; the median strut 

 or keel on the ventral aspect, of median size. Internal sac not 

 extending through the median foramen. Armature at apex of sac 

 consisting of a slender median process on which the ejaculatory duct 

 opens, two chitinous plates embedded in the membrane below the 

 median process, and a Y-piece above also embedded in the membrane. 



Polyoptilus sp. 



This is very like Mecynodera but the cap is less furcate at the 

 tip. 



Diaphanops westcrmanni. 



This is very like Pohioptilns sp. 1 ; the cap is differently shaped, 

 being broader distally and bearing there a small emargination ; the 

 armature at the apex of the internal sac (PL LXXIII fig. 205) con- 

 sists of a slender process on which the ejaculatory duct opens (a) 

 protected by a stronger and broader process above it (6), a broad plate 

 (c) grooved along the centre supports the membrane below and 

 another and smaller plate {d) supports the membrane above. N.B. — 

 In the figure, (d) and its pointing line are imperfect. 



