410 proceedings: biological society 



at the time of the Conquest. It proved to be mainly Southern Ameri- 

 can in faunal characters, with a shght admixture of North and Middle 

 America,n elements. Many South American species apparently reach 

 their northern limits here. The collections of birds and mammals have 

 been identified, and about 40 of the mammals and 30 of the birds have 

 been described as new. Among the birds are three new genera, two of 

 them of humming birds. No new genera of mammals were taken, but 

 several had not previously been reported from Panama. A new species 

 of Capyhara was among the more notable mammals. Spiny rats of the 

 genus Proechimys were found to be common. The tail, normally long 

 in this animal, is lost through some pathological condition in many 

 individuals, and owing to this circumstance the natives believe in thie 

 existence of two species. 



Goldman's paper was illustrated by lantern slide views of the country 

 explored, and of objects pertaining to its natural history. It was dis- 

 cussed by Messrs. Wetmore and Lyon. 



The third paper was by Vernon Bailey, Notes on variation, distri- 

 bution, and habits of the pocket-gophers of the genus Thomoinys. Mr. 

 Bailey said these rodents, constituting a genus of the peculiar Ameri- 

 can family Geomyidae, are distributed over the western United States, 

 extending from Alberta and British Columbia to southern Mexico. 

 They range from the Arctic-Alpine to the Tropical zonal areas and are 

 generally abundant in the regions they inhabit. They are burrowers, 

 live almost entirely underground, and are probably more restricted in 

 their individual habitats than any other of our native mammals. This 

 to some extent accounts for their great range of variation and the large 

 number of recognizable forms, nearly 90. Almost every change in cli- 

 mate, soil, and environment is reflectedby some change in the color, size, 

 proportions, or cranial characters. There is wonderful adaptation in 

 their color to that of the soil inhabited by them, varying from creamy 

 white on the light sands of the lower Colorado River flats to dark browns 

 on the volcanic plateaus of Mexico and Arizona, and almost black along 

 the humid Pacific coast region of northwestern California. There is 

 also a pure black form on the coast of Oregon which may be an extreme 

 case of dichromatism, as there are several species with a well marked 

 black phase. 



Their habit of burrowing enables the gophers to escape many ene- 

 mies and to adapt themselves to rigorous climatic conditions. In the 

 past this habit was useful in keeping the soil upturned and "ploughed," 

 but under artificial cultivation by man this habit renders the animals 

 a pest. They are very destructive to root crops, clover, alfalfa, and 

 grain. By cutting roots they often do much damage to orchards, nur- 

 series, and vineyards. They may be destroyed by trapping or on a large 

 scale by placing poisoned food in their burrows. In a revision of the 

 genus just submitted for publication as a number of the North American 

 Fauna a general discussion of the habits is given, as well as descriptions 

 of species and subspecies, and maps showing distribution. 



