Sept.-Dcc, i9i8.] Sharp: Studies ix Rhynciiopiiora. 217 



just described. The tegmen can be easily dissected off and then the 

 median lobe (ml) and its sac (is) can be seen; this lobe ("penis") 

 is tongue-like in form ; its dorsal aspect is of tough, transparent mem- 

 brane, with a stronger, chitinized yellow strip along the middle : the 

 lower aspect is membranous basally, but the sides and tip are hard 

 and dark; the struts (ms) are long, flat plates, a little longer than the 

 body of the lobe, and where they join the body a strong chitinous 

 band passes all across the dorsal aspect and from it departs the me- 

 dian dorsal strip described above, and it is also continuous with the 

 strong margin of the lowest aspect. 



The sac (is) is highly peculiar; it is shown in contraction in Fig. 

 6, and extended (but not completely) in Fig. 7, where it is seen to 

 be an elongate membranous tube, rendered irregular by projecting 

 lobes, and bearing apically a long slender flagellum (fl) at the ter- 

 mination of which is the functional orifice ; in Fig. 7 this termination 

 cannot be seen as it is twisted under the sac, but it is shown in Fig. 6. 

 This flagellum is however probably not really the termination of the 

 organ, for there is nearly certainly within it another very delicate 

 and protrusible flagellum that bears the true functional oriflce. 



The female genital structures. — The abdomen has seven visible 

 dorsal plates, six of which are membranous, the seventh, or appar- 

 ently terminal one, being chitinized and black, grooved along the 

 middle. Ventrally only 5 segments are apparent, but on taking off 

 the abdomen two others can be distinguished in close apposition with 

 the metasternum and coxae. The five visible plates are subequal in 

 length, the sutures (or rather lines of separation) are slight, and 

 have very little mobility, so that curving of the abdomen is imprac- 

 ticable. On taking off the abdomen, and examining the apex an 

 eighth abdominal segment is disclosed. The eighth dorsal is rather 

 long and hard, and its base is connected by membrane with an eighth 

 ventral, which is shovel-like in shape, and has a slender handle or 

 strut about as long as itself. This eighth ventral is connected with the 

 seventh by a very ample membrane which is folded forwards ; along 

 the middle of the shovel there is a membranous space that anteriorly 

 does not extend so far as the beginning of the strut. From within 

 the eighth segment there protrudes the termination of the genital 

 tube in the form of a pair of large corneous plates or vaginal palps, 



