(102 FAMILY XXV. UISTERIDJ';. 



e. Tibiae uU dilated, the front ones with hirge tei-minal spurs. 



VI. Deniikoi'IIimw. 



ce. Middle and hind tibise slender. 



f. Front tibiae dilated, with large terminal spur. VII. Pabomalus. 

 t.f. Front tibife feebly dilated, with small spur. Anapleus. 



TT. IIjster Linn. 1765. (L., "a clown or mimic. ") 



A x&Ty large genus, comprising about 84 of the known North 

 American species. Many of them are nominal only, being sepa- 

 rated by characters which are variable or unstable, such as the 

 length of the outer thoracic stria and the length and connection of 

 certain of the elytral striae. Since these striDS are so much used in 

 the separation of species in almost all of the genera, the following 

 brief description of them is given: 



Near each side margin of the thorax there are usually two 

 stria?, known as the "outer and inner thoracic striae." The first of 

 these is often very short or wholl3^ wanting and in the same species 

 is often variable in length. The strias of each elytron are normally 

 nine in number, but several of them are more or less abbreviated, 

 so that the number apparent is much less. Six of these, when 

 present, are found on the disk, and, beginning near the margin, 

 are called "first dorsal," "second dorsal," etc.; the sixth one, 

 nearest the suture, being known as the "sutural." The fourth, 

 fifth and sixth are often very much abbreviated. On the margin of 

 the elytron, outside of the first dorsal, there may be three other 

 sti-iff' knoAvn as the "inner, outei- and olilique subhumerals, " or if 

 only one be present, as the "subhumeral." The two dorsal seg- 

 ments left exposed by Ihe truncate elytra ai'e known as the "pro- 

 ])ygidiuni" and the "pygidium." and the character of their punc- 

 tuation is also often nsed in the se|)ai'ation of species. To obviate 

 the necessity of a very long key, the species of the genus Hister 

 have been divided into six or seven groiips or subgenera, four of 

 which are represented in Indiana. 



KEV TO INDIANA SUBGENERA OP HISTER. 



(/. Front tibiic witli llie tarsal groove liadly defined, strai.^ht; middle and 

 hind tibia? with small spines. 

 h. Mesosternuni truncate or emarginate at apex: inner thoracic stria 

 alwa.vs present, usually entire. Subgenus I. Hister. 



hi). Mesosternum more or less produced in front; inner thoracic sti'ia en- 

 tirely absent. Subgenus II. Theuster. 

 (Id. Ii'Vdut tihias with (lie t.'irsal Krouve well defined; middle and hind tibia' 

 snlHlenlate; inner thoracic stria absent, 

 c. li'nint tibia' without a tooth on the inner side near the base; spine of 

 prosternuni flattened at apex. Suligenus III. Platvsoma. 



