550 Transactions of the Society. 



It is very general in the family for the dorsal plate to be 

 narrower than the ventral at its extreme front, although it may be 

 wider below (see figs. 2, 3, 10, etc.), I only know a few species in 

 which the dorsal plate is wider in front than the ventral — M. obtusa, 

 M. turho (fig, 11a), 0. sulcata (fig. 5). In (7. ploenensis the plates 

 are exactly equal in front. 



A careful drawing should acompany every description of a new 

 species. 



LIST OF SPECIES STUDIED. 



Britain. 



Cathypna stokesii Pell. C. inermis Bryce. 



G. ploenensis Voigt. G. muscicola Bryce. 



G. hornemanni Ehr. C. hrevis sp. n. 



G. ligona Dunlop. G. spinifera Western. 



G. sulcata Gosse. Monostyla closterocerca Schmarda. 



G. depressa Bryce. M. falcata sp. n. 



G, clara Bryce. M. turho sp. n. 



Germany. 

 Monostyla constricta sp. n. 



Africa. 

 Gathypna lofuana sp. n. Lofu River, Tanganyika. 



India. 

 Monostyla cochlearis Murray. M. asymmetrica Murray. 



New Guinea. 

 Gathypna papuana s'p.n. 



United States. 



Gathypna signifera Jennings. G. stokesii Pell. 



G. ohioensis Herrick. Monostyla rohusta Stokes. 



Locality Unknown. 



Gathypna mira sp. n. In Rousselet's Collection. 

 G. hrevis sp. n. Ditto. 



Note. — All figures in the Plates accompanying this paper have 

 been drawn on a uniform scale (excepting some enlargements of 

 the toes to show details) and then reduced by photography to a 

 magnification of 260. 



