20 GEO. H. HORN, M. D. 



The species of our fauna have been studied by Dr. LeConte in 

 the Ann. Lye. iv, and later Proc. Acad. 1855. In the latter essay 

 the main divisions of Aniara have been given, but, unfortunately in 

 the specific work, no reference is made to the many important char- 

 acters discovered by Ziniinern)anii. At this point it might be men- 

 tioned that LeConte did not accept the divisions of Aviara as valid 

 genera, although many of them have been by othei- students. As 

 late as the " Catalogus," Celia is retained as distinct, but it is diffi- 

 cult to understand wiry Tricena, with a shar])ly defined structural 

 character in both sexes, should be suppressed and Celia retained with 

 a very shadowy line of den)arcation in one sex alone. 



The latest considerable study of Amara is by M. Putzeys, in the 

 Mem. Liege 1866, based almost entirely on the collection of Baron 

 Chaudoir. In this essay the author seems to have followed rather 

 closely the lines of Zimmermann with but little vai'iation. 



In the pages which follow the same general plan has been adopted 

 with some modifications which have seemed desirable, or which are 

 made necessary by material unknown to either Putzeys or Zimmer- 

 mann. 



Celia in the present essay will include Fercosia and Acrodon, two 

 other genera suggested by Zimmermann. 



Percosia was separated by having the three dilated joints of the 

 front tarsi of the male broad and cordiform, while in Celia. they are 

 said to be elongate and cordiform. As far as our species represent 

 these divisions, there is no appreciable difference betv/een them. 



Acrodon, with all the essential characters of Celia, differs in hav- 

 ing a simple mentum tooth, bifid in nearly all other Amarse. Put- 

 zeys has observed in Amathites a tendency to vary the form of the 

 acute tooth, and some of our species of Celia, notably redangula, 

 have the tooth very nearly acute at tip. 



In his division of Celia, as restricted by him, Zimmermann pro- 

 poses nine groups, the first two of which are sepaiated from the 

 others by having the hind tibije of the males slightly pubescent 

 within. For this reason I have said that the differences between 

 Celia and Amara, 2:>roper are rather shadowy. 



The first character, however, made use of in separating the groups, 

 is based on the presence of a group of small punctures, or of a punc- 

 tured fovea in the middle of the presternum of the male in seven of 

 the groups, and the absence of such structure in two others. Fnmi 

 a study of our species this character, although of great value, must 



