2 Journal New York Entomological Society, [Voi. vii. 



years later Horn in his Revision of the species of Acmaodera,^ after 

 quoting Crotch, remarks that "possibly the following pages may show- 

 quite to the contrary." The paper to a large extent fulfills the pre- 

 diction, and with a few exceptions, the species prove — notwithstand- 

 ing much variation — to be about as capable of definition as those of 

 any other genus of like extent. The student, however, who attempts 

 without some preparatory study to identify his specimens by means of 

 the tables therein given, encounters several difficulties, the chief of 

 which is the inexactness of the characters upon which the group divis- 

 ions are based. 



The tarsi in the great majority of species are said to be not longer 

 than one-third the tibiae, but in two species — comata and alacris — 

 they are longer than half the tibiae, and for this reason these two 

 species are made to constitute the group Graciliformes. As a matter 

 of fact, there is no species in our fauna with tarsi so short as described, 

 and in only two — subbalteata and opinabilis, the latter unknown to 

 Horn at time of writing — do they even approximate this condition ; 

 the great majority having the tarsi distinctly longer than half the 

 tibire. This error, however, need cause little confusion, as alacris 

 and comata are very peculiar species, separable quite as well by other 

 characters. 



The interpretation of the form of the anterior margin of the pro- 

 sternum, upon which the larger groups are based may prove more 

 difficult. Judging both from the figures and description, this primary 

 division should be accomplished with ease and certainty, but it must 

 be remembered that these figures are only conventional diagrams rep- 

 resenting typical forms which are more or less completely connected 

 by intermediates. The " Emarginata^ " while not the largest, maybe 

 regarded as a central group, characterized by the prosternum in front, 

 being nearly straight or feebly emarginate from side to side and dis- 

 tinctly retracted so as to meet the flanks at some distance behind the 

 front angles. In most species assigned to this group however, the 

 margin is faintly trisinuate and occasionally the prominence on either 

 side of the middle becomes so w^ell marked as to create a doubt as to 

 whether the form in question should be referred to this or to the 

 Sinuatae group. If the front margin is less retracted than usual, ap- 

 proach is made to the Truncatai, where it often happens that the sides 

 of the prosternum more or less obviously fail to reach the front angles. 



I Trans. Am. Ent. Soc, 1878, p. 2. 



