CRAYFISHES. 393 



100 mm. ill length according to Banta, while those from the outside do not exceed 

 84 mm. A series of fifty-eight specimens from the outside waters compared 

 with a series of six specimens from Mayfield's Cave, Monroe Co., by Mr. Banta 

 revealed the fact that the antennae of the cave specimens averaged 11.89 p. c. 

 longer than the antennae of specimens taken outside the caves in the immediate 

 vicinity. The cave series was also lighter-coloured than the series from above 

 ground. 



Cambarus graysoni, sp. nov. 



Cephalothorax robust, posterior section liigh, flattened on the back and 

 compressed laterally so that the sides are nearly vertical, giving to the whole 

 section a subquadrangular aspect; shell densely punctated on the dorsal face, 

 granulated on the lateral surfaces; distance from the tip of the rostrum to the 

 cervical groove one and one half times the length from the cervical groove to the 

 posterior end of the carapace; there are no lateral spines upon the carapace 

 and only the rudiments of the branch ostegal spines; the areola is narrow (1.5 

 mm. broad at the middle in a specimen measuring 21 mm. from the cervical 

 groove to the posterior border of the carapace) with but two rows of dots along 

 the narrow part of its course; rostrum short, margins slightly convergent, middle 

 excavated, acumen short, upturned at the tip, without lateral spines or teeth; 

 post-orbital ridges low, without spines; sub-orbital angles well marked but 

 blunt. 



Abdomen as long as the cephalothorax, smooth, pleural angles rounded. 



Chelipeds short in proportion to the body; merus short, with low tubercles 

 near the distal end of the superior margin and spines biserially arranged on the 

 lower face; carpus deeply furrowed along the upper face, armed with a 

 prominent median internal acute thorn or spine, one or two small tubercles in 

 place of a median posterior spine; an inferior median spine, with sometimes a 

 small tubercle ^jetween it and the interior median spine completes the armature 

 of the carpus; the chela is short, broad and triangular, articulated with the carpus 

 in such a way as to assume a vertical position when flexed and to form with its 

 fellow a shield or operculum appressed to the front of the Ijody; this conforma- 

 tion of the chelae is a sure token of the burrowing habits of this species; the inner 

 (or superior) margin of the palm, is very short, with a marginal row of five or six 

 low tubercles; immediately within this row (which forms a serrate edge to the 

 hand) is another row of similar though smaller tul^ercles, with vestiges of a few 

 more irregularly disposed near the articulation of the dactylus; the fingers 



