MONOTOMID^E 87 



transverse, the elytra less abbreviated and the scutellum larger and 

 more transverse. The prosternal process is scarcely at all dilated 

 apically, the tip deflexed and wholly devoid of setae, almost as in 

 Olibrus, and the rounded apex of the metasternal process, with the 

 mesosternum before it reduced to a fine bead, is also as in that genus. 



MONOTOMID^E 



Dr. G. H. Horn (Tr. Am. Ent. Soc., 1879, p. 257) treats the 

 Monotomids as a distinct family of Coleoptera, and Dr. Sharp 

 follows the same course in regard to the numerous Mexican species; 

 but, in the Henshaw check-list, they are united with the Trogosi- 

 tidse, a course that cannot be readily defended, as they differ 

 materially in facies and in many important structural features. 

 They also have some rather close relationship with Cryptophagidae, 

 as seen in the nodiform thoracic angles of Monotoma, Rlnzophagus 

 and with some of the Cucujidae in the broader extension of that 

 family. In this part of the old clavicorn series a considerable 

 number of separate family groups might be defined to include aber- 

 rant iypes, such as Monotoma, Hypocoprus and several others, now 

 representing subfamilies of the Cucujidae. The divergences are so 

 pronounced and annectent forms so uniformly wanting, that it is 

 scarcely practicable to distribute them among the larger families 

 with propriety. In the Monotomidae little or nothing has been 

 done among the American species since the Hornian monograph 

 alluded to, though in the meantime a considerable number of new 

 forms have come to light, principally in the genera Monotoma and 

 Bactridium. 



It is remarkable, but due largely to the refusal on the part of the 

 author to employ adequate optical enlargement in the study of even 

 the more minute Coleoptera,. that Dr. Horn should have rejected 

 the statement of Motschulsky and adopted the opinion of Erichson 

 regarding the formation of the tarsi in this family. The tarsi 

 are very plainly 4-jointed, the three basal joints short, not markedly 

 unequal among themselves, compactly united and together very 

 much shorter than the last ; the basal joints of the anterior are some- 

 what dilated and with an inferior brush of long stiff hairs, which is 

 sometimes visible on all the tarsi, at least in the male, and, in the 

 latter sex, the posterior tarsi are 3-jointed. At the base of the long 



