36 astacidj-:. 



tuberculato, margine interno spinis duabus, antica majori ; subtus spinis 

 majoribus duabus anticis, aliisque minoribus internis. Brachio elongato, 

 rostro longiori, extus Levi. Lotus ante apicem et margine supero tuber- 

 culato, spinis duabus anteapicalibus oblique positis; subtus biseriatim 

 spinoso. Pedibus tertiis et quartis articulo tertio unguiculato; pedibus 

 quartis et quintis capitulo basali, quartis elongatc-ovali, quintis com- 

 presso, laminato. Pedibus abdominahbus brevibus, rectis, validis. apice 

 vix-bifidis; parte externa majori. apice barbata, dentibus tribus fusco- 

 corneis, subincurvis; parte interna dente apieali acuto. obliquo, partem 

 externam fere superanti. 



Forma II. differt unguiculis pedum minoribus; pedibus abdommali- 

 bus basi articulatis. parte externa fere obtusa, dentibus obsoletis : parte 

 interna dente apieali crassiori, conico. 



Mares formae secunda? variant saepe brachio rostro breviori, inter- 

 dum cbelis brevibus, valde angustis, digitis rectis. lsevibus ; rostro 

 forma variabili, latiori, marginibus rectis vel subincurvis. acumine 

 angustiori, utrinque map-is sinuato. 



Femina differt pedibus anticis cbelisque brevioribus, extus laevioribus; 

 ventre inter pedes quartos antice tuberculo majori. postice bi-vel bisbi- 

 tuberculato : annulo ovato, fissura longitudinali, labiis alternato-intlatis. 

 Chela interdum basi rubro-maculata. 



Variet. A. 



A great number of specimens from Illinois ( Lawn Ridge, Basson 

 Ridge, Evanston, Athens, and Peoria) and from Indiana (Mus. Salem), 

 comprising both forms of the male and the female, which differ as 

 follows: The rostrum has the margins not so arcuated at the base, the 

 margins are more straight : the epistoma is often more pointed ; the 

 transverse line of the thorax is less sinuated. but usually with a lateral 

 spine. The shape of the first pair of abdominal legs is different ; seen 

 sidewise the apex more dilated, not hooked behind, the apical teeth 

 are a little larger, and pointed. The female has the ventral segment 

 between the fourth pair of legs not bituberculated, but with a slightly 

 elevated carina ; the ventral segment between the fifth pair of legs is 

 more sharply pointed, its articulation-membrane reaching farther to the 

 tip of the base of the abdominal legs. The hands often have large red 

 basal spots. 



I have seen very full-grown females, the males not so full grown as 

 those from New Orleans. 



Yarietas ? B. 



I have seen six adult females from Essex, New Jersey; New York; 

 and Beaufort, North Carolina. At first they seem to belong to an- 

 other species. The lamina of the antennae is much smaller at the tip; 

 all have a lateral thoracic spine ; the rostrum appears narrower in front 



