274 GEO. H. HORN, M. D. 



This s{)ecies has cost me a vast amount of study and trouble. It 

 has been studied from every point and the conclusion has been 

 i-eached that all the forms mentioned constitute one excessively va- 

 riable species. 



For convenience of study I have arranged the specimens in series 

 in which the general punctuation has been taken as the initial point, 

 beginning with those most coarsely punctured, arranging in a ver- 

 tical series down to those almost absolutely smooth. 



In four or five arbitrary beginnings the first specimen chosen is 

 fully colored. Then in a transverse line I have arranged the speci- 

 mens by color, and in every case end with individuals of yellowish 

 white color with the vittse barely perceptible. 



The name used for this species has generally been placed as a 

 synonym of Phyllotreta vittata, but there can be no doubt as to what 

 Say had before him from his mention of S. elongata in the descrip- 

 tion. The prominent or excurved hind angles of the thorax ai"e 

 especially mentioned, a character universal in Systena, but unknown 

 in Phyllotreta. 



In glancing over the localities for the various forms it will be ob- 

 served that the species is an inhabitant of the northern half of our 

 territory from the Atlantic to the Pacific, and from Oregon and 

 Dakota to Arizona, extending to Mexico, where it has received sev- 

 eral additional names. 



In reviewing the species of Systena recorded from Mexico by Mr. 

 Jacoby in Vol. VI, Part 1, of the " Biologia," it will be observed 

 that elongata has been identified among the collections from Guate- 

 mala. From the known distribution of this species in our fauna it 

 is highly jirobable that the species does not extend so far south. 



On the other hand discicollis, capitata and semiviftata seem to be 

 varieties of the same and correspond with those indicated under 

 tmniata. The latter species has long been known to me from many 

 parts of Mexico. 



S. marginal is Illig. — Elougate oval, rather depressed, yellowish testace- 

 ous, scarcely shining, sides of thorax and elytra narrowly hrown or piceous. 

 Antennse half as long as the body, pale yellowish testaceous, the terminal half 

 of the outer joints darker, the two basal joints brownish above. Head aluta- 

 ceous, sparsely, regularly punctate, gense smooth. Thora.v one-third wider than 

 long, not broader at base than the apex, sides regularly arcuate, margin very 

 narrow, front angles obtuse, disc moderately convex, coarsely, not closely puuc- 

 tate, color pale yellow, the margin narrowly black or brown. Elytra distinctly 

 wider at base than the thorax, humeri rounded, disc rather flat, a slight intra- 



