86 GEO. H. HORN, M. D. 



name Scymnus for those with the suture feeble at middle and pro 

 poses Scymnodes for those with the distinct suture. This character 

 fails to have any value in our series of species. 



The first ventral segment exhibits the character of greatest value 

 in the division of the species in groups. Posteriorly to the coxal 

 cavity is a slightly elevated line bea'inning at the inner edge of the 

 cavity })assing more or less obliquely and curved toward the first 

 suture sometimes joining the suture and continuous with it, or run- 

 ning parallel with the suture or recurving to the front and when entire 

 ending near the anterior angle of the segment. By some authors 

 the area enclosed by this line is spoken of as the "abdominal plate," 

 but in the present essay the more definite term " metaeoxal line" has 

 been adopted. In the species of the last two groups in this essay 

 Dr. LeConte always mentioned the sculpture of the abdominal plates, 

 but there has been observed a lack of constancy within specific limits 

 and too little variation between the sjiecies to render the description 

 valuable. As a rule, in the first two groups the area is finely punc- 

 tured, or exactly as the rest of the superficial area, while in the last 

 two groups the a,nterior portion is coarsely punctured and the poste- 

 rior comparatively smooth. 



The claws vary in form between the species and sometimes between 

 the sexes. In some of the smaller forms of the first two groups the 

 claws are simply dilated at base or feebly toothed. In the other 

 species the claws are provided with an appendix sometimes of such 

 length as to make the claw appear cleft, in these the female has a 

 shorter api)endix. Some interesting notes on this chai'acter among 

 the species ccjllected by him have been made by Mr. H. C. Fall, but 

 beyond their mention in a general way I have not been able to utilize 

 them. 



The secondary sexual characters are not, as a rule, conspicuous. 

 In the first two groups I have not observed any sexual differences. 

 In the next two groups the fifth ventral of the male is impresso- 

 emarginate in a not greatly varying degree. Occasionally the sixth 

 segment is appai'ent when the impression is somewhat cupuliform. 

 In the form considered marginicollis the male has on the first seg- 

 ment a small tubercle at middle near the suture with very short hair, 

 while in puncticollis the male has a median smooth area, on each side 

 of which is a narrow pubescent region. In cervicalls the males are 

 very evidently less broadly oval than the females. 



