Casey — A Revision of the American Paederini. 187 



species is a difficult matter and is rendered still less satisfac- 

 tory because of the complete lack of variety in the male 

 sexual characters ; to such an extent is this true that the 

 statement of these characters under each species would be of 

 little or no value, for even in the otherwise isolated pollens, 

 the only abdominal modification is the usual moderately deep, 

 broadly rounded sinus at the apex of the sixth segment, which 

 characterizes the entire genus. In my original description of 

 tantilla, the prothorax is said to be " scarcely perceptibly 

 wider than the head," but this is evidently a mistake, as the 

 head is obviously very slightly wider than the prothorax, — a 

 very exceptional character in the genus, although more frequent 

 among the minute slender forms. For the present I have 

 placed with the type of brevipenni.s, a specimen taken by my- 

 self at Lake Tahoe, differing only in a few undecisive points, 

 such as the rather less abbreviated elytra, and another 

 specimen from Coeur d'Al^ne, Idaho, which is somewhat 

 more slender in form, less densely punctate and also with less 

 abbreviated elytra. It is more than possible that each of 

 these represents a species distinct from hrevipennis, but the 

 material at hand is insufficient to warrant a description of 

 them, especially as all my representatives of this peculiar 

 group, comprising hrevipennis and quadripennis , are females. 

 There is, however, little or no observable difference between 

 the male and female in external form in those species repre- 

 sented before me by both sexes. 



Pseudomedon Key. 



In the European Catalogue of Hey den, Reitter and Weise, 

 this genus is attached as a subgenus to Medon, with which it 

 has no close affinity whatever. It is more evidently allied to 

 Caloderma than to Medon, especially in the form and wide 

 separation of the gular sutures, general facies of the body 

 and small head, but differs from both in its edentate labrum, 

 very minute and dense sculpture and strongly dilated anterior 

 tarsi. The species are few in number but occur throughout 

 the United States, as well as the palaearctic regions, the 



