280 rnncEEDixas of the national 3fCSEC}f. vol. xxv. 



postorbital ridges and sides of the carapace, as well as the lateral 

 spines of the rostrum, being strong and prominent, the branchiostegian 

 spine is small but quite evident, and the tip of the rostrum is not 

 upturned. In one male (Form I) the anterior segment of the telson is 

 trispinose on each side. The excessive spininess is doubtless due to 

 the immaturity of the specimens. 



CAMBARUS PUTNAMI Faxon. 



This species was found in abundance in the shallow side channels of 

 Green River in company with 61 rusticus. Only second-form males 

 and females were collected. In the series quite a variation in the form 

 of the ro.strum is observable; the margins in some cases being rather 

 strongly convergent, in others nearly parallel. In almost every case 

 the chelie of the luale have the lingers slightly gaping at the base. 



