1908.] i NATURAL SCIENCES OF PHILADELPHIA. 161 



ling the burrow if injured by accident, or enlarging it if outgrown (see 

 L. fatifera, etc.). 



The number of species and genera of Lycosidce is very much smaller 

 than would at first thought seem probable. These bold wanderei"s, with 

 their strong, long legs, the black spines upon which standing out 

 threateningly during excitement suggest their aggressiveness, spread out 

 persistently in e^•ery direction. Isolation of any part of a species for 

 a long time would be expected to be rare, and the establishment of 

 distinct forms, therefore, so far as dependent upon this factor, in- 

 frequent. There are comparatively few species of wide distribution, 

 rather than a large number of limited range. This wide range of 

 species is accompanied naturally by a great deal of fluctuating vari- 

 ability in many of their features. A result has been a surprisingly 

 large number of synonj^ms, consecjuent wpon examinations of limited 

 number of specimens from widely separated localities. For example, 

 species that range from New England to the West and far South 

 become lighter and lighter in coloration. In several species the 

 brightly colored individuals that prevail in Texas would appeal to 

 one at first as surely specifically distinct from the darker forms of the 

 North. But all gradations are found when sufficient material is studied, 

 especially in that from intermediate regions, while apparently no sig- 

 nificant differences at all appear in less variable structural features. 

 Important variations are discussed in detail in the present work under 

 the respective species. 



In this connection a main source of difficulty has been, indeed, the 

 placing of too great reliance upon purely relative characters that undergo 

 greater variation than has been recognized. Even in the treatment of 

 genera this purely relative nature of the characters commonly used has 

 left much room for diversity in opinion and usage. It is not, therefore, 

 really surprising to find that genera accepted without question by one 

 student are unhesitatingly denied by others. Some genera that have 

 from time to time been proposed are clearly artificial, having, it would 

 seem, been erected with a view to convenience rather than in an effort 

 to express genetic relationship. 



All of the characters that have been conmionly used in separating, 

 e.g., Pardosa and Lycosa, somewhere become uncertain, the result 

 having been many incorrect references of species. And so, also, is it 

 with other genera. My own studies of the Lycosidce long ago convinced 

 me that the clearest and most definite characters for limiting not only 

 the species but the genera of the Lycosidce as well, are those presented 

 in the copulatory organs. In the present contribution much reliance 



