276 A YEAR OF COSTA RICAN NATURAL HISTORY 



closely related species of the genus but (if I may so express 

 it) species at least once removed in relationship. The ob- 

 servation has some bearing on recent discusssions of the 

 origin of species. Those writers who believe that geo- 

 graphic, or topographic, isolation plays a great part in differ- 

 entiating species point out that it is not the most closely 

 allied species that occur together; on the contrary, the most 

 closely allied are always separated from each other by some 

 kind of barrier which prevents their intermingling or inter- 

 breeding and consequent loss of distinctness. 



The larvae of Palcsm^iema were entirely unknown at this 

 time (although we subsequently obtained them at Juan 

 Vifias) and the abundance of the winged insects, a few of 

 which had evidently only recently transformed, gave me 

 hopes of finding the early stages. But although I looked 

 long in the waters of the nearby river, under stones, in the 

 floating and submerged vegetation, and in the sheathing 

 bases of bromeliads and other plants, I was totally unable 

 to find the objects of my search. 



There was a number of brilliantly-colored day-flying 

 moths belonging to the family Syntomidae, in this strip of 

 woods. One which I secured, Cosmosoma teuthras, had the 

 thorax bright red, the abdomen black with rows of metallic 

 blue spots, the wings clear almost lacking scales except 

 around the edges, where they were reddish along the front 

 and hind edges and dark brown along the outer edge. When 

 the insect flew about, the red and blue markings were very 

 conspicuous. Another species of the same family was of such 

 interest to Mr. Schaus that I gave him the specimen. It 

 likewise had transparent wings and its general appearance 

 was wasp-like, due in large part to the way in which its 

 abdomen was marked. Although this region of the body 

 was broad at its front end as is usual in moths, the central 

 part of the abdomen was white, the sides black so that look- 



