52 PSYCHE [April 



The home of the Halisidota certainly appears to be in South America. 

 There are many forms in Central America and Mexico that require further study 

 before much can be said of their relationships, but that many of the species inhabit- 

 ing the United States originated in these countries, the offshoots of South Ameri- 

 can forms, can hardly be doubted. There is a form very closely resembling our 

 H. tessellaris and, in fact. Dr. Dyar informs me is sometimes so labeled, which is 

 found from Argentina northward, at least as far as Costa Rica. As we can trace 

 many of our species southward to Yucatan, it seems not unlikely that this may 

 prove to be the stem from which both H. tessellaris and H. citripes ^ have sprung. 

 It will be observed that the former has spread over the eastern United States, and 

 the latter to Texas and Florida, by what appear to be two separate courses, one 

 almost directly north and the other east by way of Yucatan and Cuba into Florida 

 (Atlantic Maritime, C. C. C. and a, b, on map). In the north Atlantic coast 

 region H. tessellaris has thrown off what is known as H. karrisii, the adults of 

 which cannot be separated ; but the larvae of the latter can subsist only on the foli- 

 age of the sycamore, while those of the former will perish if placed on the sycamore. 

 Halisidota caryae follows almost exactly the distribution of H. tessellaris, but there 

 is evidently a splitting up somewhere in Central America, as H. agassizii (Pacific 

 Maritime? A. A, on map), which closely resembles it, extends northward into Cali- 

 fornia, where it appears to be displaced by H. angiilifera with its variety alni, the 

 former being the low coast form and the latter the mountain form of H. viaculata, 

 which last species extending into the mountain regions of Oregon, Washington, 

 and British Columbia, sweeps broadly to the eastward through the extreme north- 

 ern United States and Canada to Nova Scotia and New England. If this theory is 

 correct, we have a species entering North America from Central America, passing 

 north along the Pacific coast to British Columbia, and making its way east and south 

 with the tide of diffusion from the northwest. Dr. Harrison G. Dyar, of the United 

 States national museum at Washington, to whom I am indebted for information on 

 this point, thinks it quite possible that H. viaculata may have originated in this 

 manner and that H. agassizii is the stem, there being somewhere to the far south 

 a connecting link between the latter and H. caryae. 



What may be termed the H. argeutata system (Tropical Subalpine, B, on 

 map) extends from southern Mexico to Vancouver, sending out H. subalpina 

 into Arizona and Colorado, and the coast species. If. sobrina, into California. 

 Another system, H. edwardsii, in all probability emanates from If. hemihyalea., in 

 southern Mexico or even farther south, extending into the Sierra Nevadas of Cali- 

 fornia, but down in Mexico ff. labeciila is thrown off, and extends along the Rocky 

 Mountains north into New Mexico and Colorado. 



' According to Dyar's latest list this is found in South America. 



