802 



THE AMERICAN NA TURALIST. [Vol. XXXVI I. 



Palseococcus is one of the few genera found fossil. Icerya is want- 

 ing in the colder parts of the Palaearctic and nearctic regions, being 

 essentially a tropical and subtropical type. 



(2.) Genera which are very widely distributed, but not 

 cosmopolitan. 



Margarodes, 10. Europe, Africa, America. 



Orthezia, 19. Palaearctic, Nearctic, Neotropical. 



Rhizococcus, 14. Europe. Xew Zealand, Australia, Texas; but 



the species may not be strictly congeneric. 

 Sphaerococcus, 19. Australia, Japan, North America. The 



Ceroputo, 7. Europe; North America, extending into the Neo- 

 tropical region. 



Ripersia, 37. Holarctic, New Zealand, Australia, and doubt- 

 fully congeneric species in India and Trinidad. 

 Tachardia, 24. Cosmotropical. 



Lichtensia, 12. Holarctic and Neotropical, but mainly the lat- 

 ter, if the species are really congeneric. 



Ceroplastes, 62. Very abundant in the Neotropical region, 

 extending into the warmer parts of the United States; Medi- 

 terranean region to South Africa; a few species in Asia and 



Phenacaspis, 15. North America, Asia, S. Africa, Australia. 

 Chrysomphalus, 31. America, Australia, Asia. Numerous in 

 Mexico. 



Targionia, 18. Holarctic, Australia, India. 

 The doubt expressed as to the species of certain genera properly 

 belonging together rests on the fact that the generic characters seem 

 more or less artificial or arbitrary, and may include species which 

 have independently come to have certain peculiarities. Thus, Rhi- 

 zococcus is essentially an Eriococcus without a sac ; but we do not 

 know that the sac might not be independently lost in different parts 

 of the world. The only way to settle these matters is by the study 



(3.) Genera having few species very widely separated. 



Tessarobelus, 2. One in New Caledonia, one Panama. Prob- 

 ably they are not strictly congeneric. 



