ioo MEMOIRS ON THE COLEOPTERA 



striae as in ephippigerum; pygidium very coarsely, closely punctate; 

 basal segment of the abdomen with well separated and moderate 

 elongate punctures, those of the fifth very coarse and crowded, 

 those of the three series oblong and close-set; inner line of the post- 

 coxal plaques extending about to the apex of the segment; tarsi 

 notably slender, more so than in any of the preceding species. 

 Length (cf) 1.35 mm.; width 0.35 mm. Arkansas. A single ex- 

 ample curtipenne n. sp. 



The species named convexulum above, is that usually identified as 

 striolatum Rttr., but it does not agree at all well with Reitter's 

 description of striolatum (Verh. Nat. Vereins, Briinn., 1872, p. 14). 

 The size is not so large (2 mm.) and striolatum, the locality of which 

 was unknown, was described as depressed, the head and pronotum 

 rather closely punctate, the former fully as wide as the latter, or 

 wider in the male, and the prothorax "fast etwas breiter als lang," 

 which would be very misleading if applied to the notably transverse 

 prothorax of convexulum. Then again, the elytra are said to be 

 "subtiliter striatis, striis subtilissime punctatis," which will not 

 answer to the rather strong and distinctly punctured striae of con- 

 vexulum. As shown above, there are several species having the 

 loosely serial punctuation of the elytral flanks, which was un- 

 doubtedly the character relied upon by Dr. Horn for the identi- 

 fication of striolatum; perhaps it would have been better to classify 

 the species of the above table primarily upon the radical differ- 

 ences in the sculpture of these flanks of the elytra, but this did 

 not occur to me until afterward and the arrangement adopted will 

 answer for the present. 



Pycnotomina n. gen. 



The type of this proposed genus is the Bactridium, cavicolle of 

 Horn. In general habitus, due to its broad form and dorsal con- 

 cavity, it presents a radically different appearance from Bactridium 

 and, structurally, it differs in having the front of the head acutely 

 ogival in outline and not broadly and arcuately obtuse. As 

 minor differences it should be said that there is no trace of the 

 micro-reticulation of the integuments, universally visible in Bac- 

 tridium, and the elytral striation is obsolete, leaving simply the 

 regular series of punctures. In the structure and peculiar sculpture 

 of the abdomen, in the legs and antennae and the oblique impression 

 extending outwardly from the anterior acetabula toward the hind 



