164 JOURNAL OF ENTOMOLOGY AND ZOOLOGY 
is their service to remove the waste of ocean life. The latter are 
free swimmers and in their wanderings scour the surface of the 
waters. The former usually remain close in their native haunts 
and it is they who purify the substrata of the sea. Not here 
does their service end. So abundant are they that they form a 
part of the food of many fish and thus they are indirectly food 
providers for men. To these ends the Isopoda are very widely 
distributed. They are most abundant in the northern waters. 
Thence they extend in varying numbers to the warm southern 
waters and the temperate shores and from east to west. So 
great is their importance that we dare not speculate as to the 
state of unstable equilibrium in nature which their sudden and 
thorough destruction would cause. Suffice it to say, that at 
present no such calamity is pending, for the isopods are a 
mighty throng and well equipped by nature to survive. 
In the studies which follow I have described and illustrated 
twelve species collected at Laguna Beach, California, in the 
summer of 1911. One of these is a new species, two are new 
varieties. A number of the others, although noted before, have 
not been illustrated at all before or if so not at all completely. 
List OF THE SPECIES REPRESENTED IN THIS STUDY 
Superfamily FLABELLIFERA 
A. Family CIROLANIDA 
Genus Cirolana 
Cirolana harfordi (Lockington) 
B. Family SPHAZROMIDA 
Genus Dynamene 
Dynamene glabra Richardson 
Superfamily VALVIFERA 
A. Family IDOTHEIDA 
a. Genus Idothea 
Idothea rectilinea (Lockington) 
b. Genus Pentidotea 
