178 Journal New York Entomological Society. t^'°i- xxvi. 



The peculiar armature of this insect makes it very distinct but the 

 deeply pitted pronotum shows its relationship to the preceding. In 

 the characteristics of the posterior lobe it shows an approach to the 

 Mexican 5". hiauriciilata Champ., but it has a much simpler type of 

 anterior lobe than has the species from farther south. The uni- 

 colorous elytra also separates it. (Plate IX, fig. 2.) 



Silis bidentata Say. 



Cantharis? bidentata Say., Journ. Acad. Nat. Sci. Phila., Vol. \^, p. 169 ; 

 Ed. Lee, Vol. II, p. 278. 



Silis lepida Dej., Cat., 3d Ed., p. 121. 



Silis bidentata Say, Proc. Acad. Nat. So. Phila., Vol. V (1851), p. 339. 



Ditemniis bidentatus Lee, Class. Col. N. Am., Smith. Mis. Coll., Vol. Ill 

 (1861-62), p. 189; Trans. Amer. Ent. Soc, Vol. IX (1881), p. 58. 



This common Eastern species seems to be distributed throughout 

 the Middle and South Atlantic States and along the western flanks 

 of the Alleghany Mountains, but from Indiana west to the Rockies 

 it appears to be replaced to a great extent by the following. It is 

 also fairly constant though the color of the head is apt to be red in 

 the northern specimens and piceous in the southern specimens. (Plate 

 IX, fig. 14.) 



Silis latiloba Blatch. 



Ditemnus latilobus Blatch Col., Indiana, p. 837. 



This differs from the preceding mainly in being larger, in having 

 the head uniformly piceous, the posterior lobe of the lateral thoracic 

 armature more than twice the width of the lobe in front and with its 

 outer margin obliquely truncate, and the lateral extension of the 

 apical margin less lobe-like. It was described from Indiana but speci- 

 mens have also been seen from Minnesota, Iowa, Nebraska, and Mis- 

 souri. It seems to be rather common in Missouri. 



Silis obtusa Lee. 



Ditemnus obtusns Lee, Trans. Am. Ent. Soc, Vol. V (1874), p. 62. 



The prothorax broadly bordered with black, the entire absence of 

 lateral lobing to the anterior margin, the broader anterior lobe of the 

 armature and its projection backwards, the smaller and more hook- 

 like posterior lobe, and the deep and rounded median fossa, distinctly 

 separates this species from either of the preceding two. It is found 

 in both middle and southern California, but is more common in the 

 latter region. (Plate IX, fig. 15.) 



