62 COSTA RICAN DIPTERA 



ing in on the ventral plates. The second and third segments 

 have a more or less distinct, sunken area on their dorsum. The 

 genus should not be confused with Gastrops, which has a promi- 

 nent subhemi-spherical swelling on the face. 



The Costa Rican species may be separated as follows: 

 Scutellum convex, shining, mesonotum smooth; legs entu-eh' j'ellow. pallipes 

 Scutellum flat, more or less opaque; mesonotum sculptured or oi^aque. 



Femora and tibiae black willistoni 



Legs entirely yellow granulosus 



Lytogaster granulosus Cresson 



191-4. Lylogader granulosus Cresson, Ent. News, xxv, 249. 



Legs entirely yellow, but the scutellum and mesonotum opaque 

 on account of the, granulose sculpturing. The abdomen is'not so 

 convex as in the other species. 



Originally described from Costa Rica. 



Represented by 10 specimens from the following localities: 

 In forest near Guapiles, June 4; Near Rio Reventazon at Juan 

 Vinas, June 28; Bonnefil Farm, Rio Surubres, October 20; Upper 

 Reservoir, Banana River, November 9; Beaches on back chan- 

 nel of Rio Reventazon, Cachi, March 7. 

 Lytogaster willistoni Cresson PI. Ill, fig. 18. 

 1916. Lytogaster vdllisloni Cresson, Ent. News, xxvii, 150. 



Distinguished by its black legs and antennae, and unusually 

 convex development of the fourth abdominal segment, which is 

 also distinctly pitted and shining. 



Originally' described from California. 



Represented by five specimens from the following localities: 

 Over mud at Cartago, February 19; Laguna del Dirumbo, south- 

 ern slope of Irazii, July 13; Over mud on southern slope of Irazti, 

 near Cartago, Deceml^er 15; Along Brook Toyogres on southern 

 slope of Irazu, April 6. 

 Lytogaster pallipes Cresson 

 1914. Lytogaster pallipes Cresson, Ent. News, xxv, 248. 



A species distinguished bj' the shining mesonotum and yellow 

 legs. The abdomen is stronglj^ convex as in unllistoni. It 

 should not be confused with granidosus. 



Originally described from Costa Rica. 



