78 THE NAUTILUS. 



path, to see him before treading upon him. Secondly, because if 

 you carelessly step on the little round cactus so common in this 

 region, the spines, if they do not puncture the sole of your shoe, will 

 penetrate the upper leather more surely than needles. In the eyes 

 of an eastern collector, accustomed to look for land shells in moist, 

 shady places, it is not a promising country. There are no Avoods, 

 except on the mountains, and few streams of water around whose 

 banks mollusks might be expected. Yet there are shells all around. 



Find a cactus that is dead, and turn over its fallen leaves with a 

 stout stick. Like the watermelon, a cactus seems to carry its own 

 Avater, and under this moist, decaying mass the little Pupas may be 

 found, and Helix Stearnsiana Gabb takes shelter from the sun. The 

 night dews are heavy, and doubtless Avhen darkness falls, the snails 

 emerge from their hiding places, and browse around for food. 



Another favorite collecting ground is a pile of loose rocks ; if on 

 the south side of a hill, where the sun beats hottest, so much the 

 better. Turn over every stone until the damp earth is reached, and 

 your eyes will be gladdened by the sight of the elegant dark brown 

 shiny Glyptostoma Newberryana W. G. B. If the rocks are in the 

 midst of shrubbery and herbage, the large beautifully banded Arianta 

 tudiculata Binn. is likely to be found. Very rarely do any of these 

 shells live on the shaded northern slopes, doubtless because where the 

 ground is less heated during the day, less moisture is condensed at 

 night. In this country, then, the collector truly earns his prizes by 

 the sweat of his brow. 



One other land shell is the Succinea Oregonensis Lea, of a red- 

 dish golden hue, found on the weedy river banks, and living only a 

 little less in the water than its frequent companions Limnaa 

 Adelinse Tryon, and Physa Gabbii Tryon. These are the common 

 shells of the open country, although far from numerous in individuals, 

 when one considers the hours of diligent labor necessary to procure 

 a reasonable number. 



WHAT IS A SPECIES T 



BY CHARLES T. SIMPSON. 



In view of the practice of naming everything now-a-days by the 

 so-called neAV school of conchologists, we may well ask the above 

 question. Agassiz in classifiying animal life says, that "species are 



