132 ZOOLOGY. 



laying up pellets of pollen in some subterranean mouse, 

 nest or in a stump, and the young hatching, gradually eat 

 the pollen, and when it is exhausted and they are fully fed, 

 they spin an oval cylindrical cocoon; the first brood are 

 workers, the second males and females. The partly hex- 

 agonal cells of the stingless bees of the tropics (Melipona) 

 are built by the bees, while the hexagonal cells of the honey- 

 bee are made by the bees from wax secreted by minute 

 glands in the abdomen. Though the cells are hexagonal, 

 they are not built with mathematical exactitude, the sides 

 not always being of the same length and thickness. 



The cells made for the young or larval drones are larger 

 than those of the workers, and the single queen-cell is large 

 and irregularly slipper-shaped. Drone-eggs are supposed 

 not to be fertilized. Certain worker-eggs have been known 

 to transform into queen-bees. On the other hand, worker- 

 bees may lay drone-eggs. The maximum longevity of a 

 worker is eight months, while some queens have been 

 known to live five years. The latter will often, under fa- 

 vorable circumstances, lay from 2000 to 3000 eggs a day. 

 The first brood of workers live about six weoks in summer, 

 and are succeeded by a second brood. 



Literature op Artiiropoda. (For Crustacea see p. 85.) 



Podosiomata. — Van <ler Hoeveu's Reeberches sur l'Histoire Natu- 

 relle des Limules, 1838; Milne-Edwards's Recbercbes sur l'Ana- 

 tomie des Limules, 1872; Packard's Four Memoirs on tbe Anatomy 

 and Embryology of Limulus, 1872-91; Kingsley's Notes on tbe Em- 

 bryology of Limulus, 1885; works of Walcott, Dohrn, Lankester. 



Arachnida. — Hentz's Spiders of the United States, Boston, 1875; 

 Emerton's Structure and Habits of Spiders, 1883, and bis various 

 essays, witb those of G. W. and E. G. Peckbam; McCook's American 

 Spiders and their Spinning Work, 3 vols., 1889-92; with tbe works 

 of Walckenaer, Blackwall, Thorell, Simon, Keyserling, Marx, etc. 



Myrictpoda. — Wood's The Myriapoda of North America, 1865; with 

 essays by Newport, Harger, Latzel, Haase, Packard, etc. 



Tnsecta. — Kirbyand Spence's Introduction to Entomology, 4 vols., 

 1828; Burmeister's Manual of Entomology, 1836; Westwood's Modern 

 Classification of Insects, 2 vols., 1839-40; Harris' Treatise on In- 

 sects injurious to Vegetation, 1886; Packard's Guide to tbe Study of 

 Insects, 1888; Entomology for Beginners, 1890; Graber's Die In'sek- 

 ten, 1877; Lubbock's Ants, Bees, and Wasps. 1882. For economic 

 entomology, tbe works of Harris, Fitch, Riley, Le Baron, Liutuer. 



