No. 453-] 



DISTRIBUTION OF CICINDELA. 



We have here, then, a great enclosed region which, though 

 comparatively open to migrations from the north and south, is 

 nearly closed against encroachment from the east and west 

 except in those cases where man may be conceded to have been 

 a factor. We should expect the more characteristic forms to 

 show extensive north and south distribution or that they may be 

 confined to the basin and the more accessible adjoining areas. 

 Some species no doubt originated, as such, within the limits of 

 the basin proper, and I believe that, in some cases at least, we 

 can determine which these are. It is with certain forms of this 

 nature — that is to say with true indigenes — that we have now 

 to deal. 



Two types of littoral beetles may be said to be very character- 

 istic of the Great Basin and to be dependent upon the peculiar 

 conditions that occur there in the way of sei 1 Ik 1 Hits 



in connection with springs and lakes. These are the Cicindela; 

 of the echo type and the species or subspecies of Tanarthrus 

 which belong with T. salicola. Neither of these genera is con- 

 fined to the basin, Cicindela being of wide distribution and 

 evidently of southern origin, while Tanarthrus is not known out- 

 side of the southwestern United States. Iksidcs the forms of 

 this latter genus described from the lake shores of the (jreat 

 Basin, a few species of somewhat different aspect are known to 

 occur in saline spots in California and Arizona. I'he species ot 

 Bembidium of the henshazvi type have also, \\\ niy o] union, 

 attained their present specific structures withm the hunts ot the 

 Great Basin and are not to be considered mi,i,nants honi the 

 outside. For the present, I prefer to leave out ot the disi usskmi 

 all of those Coleoptera not directly connected with the existem e 

 of alkaline and saline lakes, since the problem of their dis])ersal 

 or distribution is different, in some respects, from that con- 

 cerning the littoral forms and needs a separate body. 



I am prepared to go farther than the simple statement that 

 we can correctly indicate certain species as having arisen, as 

 such, within the limits of the Great Basin. I believe it is also 

 possible to show that some of these have been inhabitants of the 

 region for long periods of time, and that in the course of their 

 existence they have been played ui)on by con.litions which arose 



