THE GENUS CALOSOMA. 19 



side. Posterior median plates rather oval in form save on sixth and 

 seventh segments, where they appear somewhat truncate on inner mar- 

 gins; plates with broad median line of separation in well-fed larvae. 

 Posterior angles of anal segment pointing backward rather promi- 

 nently. (PI. XI, B.) 



(Introduced and established in New England) C. sycopJianta. 



Anterior ventral plate of first to seventh abdominal segments oval, with 

 noticeable dilation on anterior middle margin. Outside posterior 

 ventral plates of same segments round to approximately square, often 

 with broad and shallow notches on inner margins. Posterior median 

 plates square to rectangular, truncate on inner margins of first 7 seg- 

 ments, plates with narrow median line of separation in well-fed larvae. 

 Posterior margin of anal segment truncate, posterior angles not pointing 

 prominently backward. (PL IX, P>.) 

 (Eastern, southern, and central United States and Canada). C. scrutator. 

 Dorsum brown to blackish-brown in second and third stages. Full-grown larvae 

 less than 30 mm. long. 

 Caudal appendages stout, almost straight. Dorsal protuberances prominent, 

 erect, locatea two-thirds length from base to apex. 

 Posterior angles of anal segment obtuse, not prominent and not pro- 

 truding prominently backward. 



(Eastern, southern, and central United States) C. wilcoxi. 



Posterior angles of anal segment acute and extending backward rather 

 prominently. 



(Europe, introduced into Massachusetts) C. inquisitor. 



Caudal appendages long, acute, usually slender. Dorsal protuberance short, 

 stout, pointing slightly backward, located about one-half length from base 

 to apex. 



(Northern United States and Canada) C. frigidum. 



Without reddish-brown patch at base of caudal appendages in second and third stages. 

 Dorsum bronze to blackish-bronze in all stages; more prominent in second and 

 third. 

 Caudal appendages very long, slender, slightly curved upward. 



(Japan) C. chinense. 



Dorsum dull or shining black in all stages. 



Caudal appendages short (less than 2 mm.), stout, curved slightly downward 

 from base to apex. 

 Anterior ventral plates of first to seventh abdominal segments dilated 

 at center, especially on anterior margins. 



Posterior median plates of abdominal segments 2 to 7 inclusive with 

 both median anterior and posterior angles rectangular. 



Dorsal protuberance of caudal appendages stout, acute, rather 

 erect, located in middle. Posterior angles of anal segment 

 almost truncate. Larva robust. Dorsum dull black. 



(Northern, eastern, and central United States and Canada. 



C. caliduw.) 

 Dorsal protuberance of caudal appendages stout, acute, rather 

 erect but located two-thirds length of appendage. Posterior 

 angles of anal segments acute. Larva rather elongate. Dor- 

 sum shining black. 



(Rocky Mountain section and southwestern United States.) 



C. obsohium. 



Posterior median plates of abdominal segments 1 to 6 inclusive with 



median anterior angles rectangular and posterior angles rounded. 



Dorsal protuberance of caudal appendage short, stout, rather 



erect. Abdominal segments 1 to 8 each containing from four 



to ten small plates near lateral apices of anterior ventral plate. 



(Pacific slope, Rocky Mountain section and the southwestern 



United States) C. ccnwtllatum. 



Dorsal protuberance of caudal appendage rather long, stout. 

 extending backward in a straight line from basal halt of 

 appendage. Abdominal segments 1 to S each containing from 

 two to five small plates near lateral apices oi anterior \ eutral 

 plate. 



(California and Idaho) C. sen. I 



