Mr. F. Walker's Characters of undescribed Diptera. 269 



tarsi's albis apice nigris, alls obscure cinereis, stigmate ve- 

 nisque nigris, lialteribus tesiaceis apice nigris. 



Female. — Black : head testaceous, paler hindward ; antennas 

 black, longer than the breadth of the head ; pectus with whitish 

 tomentum ; scutellum with two stout spines ; abdomen blue, much 

 broader but hardly longer than the thorax ; tip attenuated ; fore- 

 knees whitish ; tarsi white, with black tips ; wings dark grey ; 

 stigma and veins black; halteres testaceous, with black knobs. 



Length of the body S\ lines ; of the wings 7 lines. 



Mexico. 



This is nearly allied to C. caripea, Gerstacker, but may be dis- 

 tinguished from that species by its black thorax. 



Note, — Two works on Diptera have appeared since these de- 

 scriptions were offered to the Entomological Society. 



The first is, " Catalogue of the described Diptera of North 

 America. Prepared for the Smithsonian Institution by R. Osten 

 Sacken." This work includes the Diptera of Mexico, of Central 

 America and of the West Indies^ and indicates, as far as possible, 

 the locality where each species has been discovered, and the in- 

 stances of the extension of its range to South America, and thus 

 brings together large materials for the knowledge of the geo- 

 graphical distribution of species. 



The other work is " Saggio di Ditterologia Messicana di Luigi 

 Bellardi, Professore di Storia Naturale. Parte 1*. Torino. 

 1859." 



The first part contains the Nemocera, and the families Slra- 

 tiomidce, Tahanidce and Acroceridce of the Brachycera. The 

 descriptions are distinct and complete, and are accompanied by 

 two plates, in which the characters of the species are very well 

 delineated. 



Genus Stratiomys, Geoffr. 



Stratioinys constricta. 



Mas. — Atra, capite antico sub-argenteo, scutelli spinis duabus 

 piceis, abdominis segmentis sub-argenteo-fasciatis, apice piceo, 

 tibiis posticis tarsisqiie fulvis, alis obscure fuscis basi luridis 

 apices versus limpidis. 



Male. — Deep black : head with slightly silvery tomentum in 

 fiont, and with grey pubescence beneath and behind; scu- 

 tellum with two piceous spines ; abdomen piceous at the tip, 

 and with a band of slightly silvery tomentum on each segment ; 

 tarsi and hind tibiae tawny ; wings lurid at the base, dark brown 



