Sept.-Dec, I9i8.] VaN DyKE : REVIEW OF GeNUS SiLIS. 165 



The ante-basal fllamentous process very short and but slightly curved. 



Length 4.75 mm. (Panamint Valley, Inyo Co., Cal.)..S. filicornis n. sp. 



14 — Upper surface mostly pale yellow. Length 5-6 mm. (Western Ore. and 



North. Cal.) S. lutea Lee. 



Upper surface black with pronotal disc yellow. Length 5-6 mm. 

 (Locally along extreme coastal strip from Santa Barbara Cal. to 



Wash.) S. lutea var. filigera Lee. 



15 — Prothoracic incisure widely opened externally 16 



Prothoracic incisure almost completely closed by anterior and posterior 



process . ^ 17 



16 — The anterior process angulated and directed slightly backwards, the pos- 

 terior, long, straight, and narrow, directed directly outwards from be- 

 neath posterior angles. Length 7 mm. (Argus Mts., Cal.) 



S. deserticola n. sp. 



Both anterior and posterior processes lobed and directed outwards. Black 



with pronotum orange red. Length 4.5 mm. (111., Ind., East. N. Y. 



to N. Car.) S. spatulata Lee. 



17 — Apex of prothorax much narrower than base, sides widely diverging back- 

 wards, the anterior process of incisure projecting outwardly beyond 

 normal side line of prothorax and curving backwards until it almost 

 meets the basal process. Length (>-■] mm. (Northern Ariz.) 



S. arizonica n. sp. 

 Apex of prothorax but little narrower than base, sides but slightly di- 

 verging backwards, the anterior process projecting obliquely backwards 

 without interrupting the normal side line of prothorax and meeting the 

 hook-like extension of the basal process. Length 5.5 mm. (San Ja- 

 cinto Mts., Cal.) S. fenestrata n. sp. 



18 — Posterior margin of prothorax broadly rounded, posterior angles small 

 but evident, both processes broad, the anterior always ear-like, the 



antennas quite filiform 19 



Posterior margin of prothorax more or less truncate at middle, antennae 



robust and quite serrate 23 



19 — Disc of prothorax convex without deep median fossa 20 



Disc of prothorax with deep and broad median fossa 22 



20 — Species bicolored, black and orange 21 



Species entirely black, the anterior and posterior processes both long and 

 approaching each other, antennae as long as the entire body. Length 

 6.5 mm. (Huachuca and Pinaleno Mts., Ariz.)...S. nigerrima Schaef. 

 21 — The anterior process not reaching the blunt triangular posterior process, 

 the incisure therefore open, the antennae reaching slightly beyond mid- 

 dle of body. Length 5 mm. (Huachuca and Chiricahua Mts., Ariz.) 



S. abdominalis Schaef. 



The anterior process overlapping apex of long posterior process, thus 



making a fenestra of the incisure, the antennse almost reaching end of 



body. Length 6 mm. (Tex.) S. perforata Lee. 



22 —The anterior process hardly projecting backwards, the posterior long. 



