﻿76 FIELD AND FOREST. 



This crab not only contributes to the sustenance of man ; it forms 

 the most abundant food of a great proportion of the other tenants of 

 the seas. Perhaps no creature of the water multiplies in such count- 

 less swarms. Were it not for the great number of enemies which are 

 ever on the alert to devour it, the sea might be crowded so full of crus- 

 tacean forms as to leave no room for other animals. 



However, it is probable that not the one-hundredth part of the ripe 

 females are able to remain undisturbed long enough to hatch their 

 eggs. Skates, Rays and other monsters of the deep are continually 

 searching for them, and nearly all the varieties of our larger food-fishes 

 pursue them to destruction. The patient females hide in the sea-weed 

 or bury themselves in the mud to escape their persecutors, but rarely 

 do they succeed in evading them. When aroused they may protect 

 themselves and eggs with savage energy, but in general they remain. so 

 quiet as to be touched by the foot without causing them to show signs 

 of irritation. 



Philip R. Uhler. 



Sexual Variation in the Genus Leucosticte. 



In Mr. Ridgway's recent reply * to my critique f upon his "Mono- 

 graph of the Genus Leucosticte,' 1 '' he states, very truly, that " the point 

 at issue is, whether the sexes of ' tephrocotis ' and ' littoralis ' do, or do 

 not, differ in plumage," and, he should have added, in size. Having 

 shown, in my above-cited paper, that there exists in these forms the 

 usual amount of sexual variation in size found in this genus, and that 

 there is also a well-marked sexual difference in color, Mr. Ridgway 

 attempts to avoid a full admission of the correction by saying that this, 

 " in a diagnostic sense, means whether there are, or are not, absolutely 

 constant sexual differences!" Under the heading "Sexual Differ- 

 ences," Mr. Ridgway, in his Monograph, j says: " The American 

 species of this genus fall into two distinct groups according as the sexes 

 do or do not differ in appearance. In L. tephrocotis — in all its forms — ■ 

 there is not the slightest sexual difference § ; but in L. atrata and L. 



* This Journal, September, 1876. 



f Bull. U. S. Geol. and Geog. Survey of the Terr., Vol. II., No. 4, pp. 345-350. 

 % Bull. U. S. Geol. and Geog. Survey of the Territories, 2d Ser., No. 2, p, 60. 

 \ Not italicised in the original. 



