4 GEO. H. HORN, M. D. 



Considerable stress has been laid on the fact as to whether the base 

 of the thorax has a marginal line, but as far as our species are 

 known to lue it exists in all, but varies in the sharpness of its defi- 

 nition. 



With the structural characters already referred to it is proposed 

 to arrange our species in the following manner : 



Stridulating ridge of first ventral segment incomplete, i. e., extending from the 

 front angle in a curved line merely to the posterior border of the segment. 



Heterocerus. 



Stridulating ridge of first ventral segment complete, i. e., forming nearly a semi- 

 circle from the front angle to the posterior border, then recurving to the 

 inner coxal border Liitloriiiiiis. 



All our species belong to Heterocerus proper^ excepting auromi- 

 cans, which belongs to Littorimus. 



The species of Heterocerus proper may be separated in the follow- 

 ing manner : 



Subgenus HETEROCERUS. 



Metasternum without post mesocoxal line 2. 



Metasternum with post-mesocoxal line 5. 



2. — Labrum of male narrowed at tip and prolonged in a process of greater or 



less length 3. 



Labrum of male not prolonged in a process 4. 



3.— Process of male labrum long and narrow giiatho. 



Process of male labrum not longer than half the body of labrum, and not 

 abruptly formed. 

 Elytra in greater part pale, with indistinct fuscous markings ; thorax with 



sides broadly paler pallidas. 



Elytra piceous, with the usual pale fasciae more or less developed. 



Teiitralis, 

 4. — Mandibles not prominent in male ; elytra never with juxta scutellar spot. 



tiiidattis. 



Thorax with entire pale border var. undatus. 



Thorax with front angles yellow var. mollinus. 



Thorax entirely piceous var. fatuus. 



5. —Mandibles of male without basal lobe extending over the labrum 6. 



Mandibles of male with basal lobe 10. 



6. — Epipleurae with oblique elevated line near the base; thorax entirely pice- 

 ous; elytra without juxta-scuiellar spot g'eiiiiiiattis. 



Epipleurffi without oblique elevated line 7. 



7. — Elytra without juxta-scutellar pale spot. 8. 



Elytra with juxta-scutellar pale spot 9. 



8. — Large species; legs more or less piceous; elytra usually substriate, the pale 



fasciae much broken and never broad bi'iiililCUS. 



Smaller species; legs entirely pale; elytral markings well defined and 

 broad, usually entire, surface not substriate Scliwarzi. 



