454 PROCEEDINGS OF THE \ ITIONAL UUSEl 1/ . vol 38. 



Now although the typical L. arcuata, of Scudder differs rather decid- 

 edly from what has always been regarded as L. chalybea, I have 

 examined specimens from various localities, which (ill in the gap, and 

 in some cases both forms are taken together. 



The typical L. arcuata form is rather large, broad, with more or 

 less dilated abdomen, brownish color, strong pubescence, and 

 strongly bowed forceps, often with a small tooth. 



The typical L. chalybea is narrower, the abdomen not dilated, the 

 elytra steel-blue, feebly or not al all pubescent, the forceps unarmed 

 and gently arcuate. 



It will be admitted by all that the curvature of the forceps, the 

 intensity of coloration, and strength of the pubescence an 1 unstable 

 characters. 



Accordingly, we turn to the pygidium to decide the question. 

 Now, here I am compelled to admit that even the pygidium fails 

 through instability of form. 



I possess in my own collection two fine males of the undoubtd 

 L. arcuata form, both taken by Mr. \V. F. II. Rosenberg at an eleva- 

 tion of about l.ono feet, at Chimbo, in Ecuador, in August, 1897. 

 In one the pygidium is very broad and swollen at each side into a 

 blunt, thick tubercle; in another the pygidium is less broad, trun- 

 cate, with a lint* point at each corner. This is the pygidium that we 

 associate with L. chalybea, but the general form and color of the body 



is decidedly that of L. arcuata. 



I have seen both forms of pygidium also in specimens from Mexico. 

 The small, steel-blue forms which are generally called L. chalybea 

 have the two-point pygidium; the L. arcuata form has it as often as 

 not. Therefore we can not distinguish the two by the forms of the 

 pygidium of the male. 



In Dohrn's original female in t ho Vienna Museum the pygidium is 

 narrower, bluntly conical, with two minute points at the apex. Two 

 of Caudell's females from Guatemala of the L. chalybea form but 

 Labeled L. arcuata, have a broader, truncate pygidium, with a line 

 point at each corner. 



Borelli's specimens of L. chalybea from Paraguay have the trun- 

 cate two-point pygidium in the male, but t ho female has a simple 

 conical pygidium. 



If we regard /.. chalybea as distinct from /.. annulata, basing our 

 separation on the form of the pygidium, we must disregard the other 

 features of size, color, and pubescence. If we follow them, we must 

 disregard the form of tin* pygidium. 



In his description of /.. arcuata Scudder refers to the pygidium of 

 the male as "verj broad, bifid, with large teeth." Dohrn does not 

 refer to this organ in his description of L. chalybea. 



In de Bormans' manuscript album, now in my possession, there 

 are colored draw inns of the male of each form and outline sketches of 



