2 • GEO. H. HORN, M. D. 



The strife which are characteristic of this group extend from the 

 tip of the prosternum to the beginning of the lobe, and are divergent 

 at each end, more so posteriorly. In the first two species the striae 

 are hooked at the anterior end and their tips thus approach, in dcfectus 

 they are divergent and not hooked. 

 H. servus, Er.— West Indies, Maryland, Arizona. 

 H. indistinctus, Say,— N. C, Ga., N. M, 

 H. defectus, Jjec— Mass., S. C, Ga. 



I have in my cabinet a specimen with the last two dorsal segments 

 coarsely and densely punctured as in servus but with the outer thoracic 

 stria short as in defectus. I do not care to give this a name until other 

 specimens appear when it may possibly be 'necessary to unite those 

 already named instead of describing new species. 



Revision of tlie species of ACM.KODERA of the 

 lJnite«l States. 



BY GEORGE H. HORN, M. D. 



The number of new species which have accumulated in our collec- 

 tions since the latest synopsis (Leconte, Trans. Am. Philos. Soc. 1859), 

 has nearly equalled the nuuiber then known and of these fourteen 

 have remained to the present time unnamed. While feeling the neces- 

 sity of having these described I have until now been deterred from 

 attempting any arrangement of our entire series by tlie remarks of 

 Mr. Crotch (Proc. Acad. 1873, p. 89), as follows : " but I am entirely 

 unable to discover any characters except the variable ones of color, 

 sculpture and form ; so that the limits of species appear to be merely 

 opinionative." Possibly the following pages may show quite to the 

 contrary. 



As there is considerable structural variation the difi"erent members 

 of the body will be reviewed. 



The head is always punctured, the front either impressed or convex 

 and the vertex usually finely carinate, either deeply inserted with 

 the eyes partly concealed by the angles of the thorax, or with the 

 eyes free. 



The thorax is very variable. When viewed from abtive the apex 

 may be emarginate as in the sinuate and enianjinatse or truncate as 

 in the fnmcatse; sometimes the middle of the anterior margin is 

 slightly prolonged. The sides vary in form from strongly arcuate to 

 nearly straight, and the margin may be broad and distinctly reflexed 

 or very narrow, often entirely invisible from above or even nearly 



