08 ASTACID^. 



apicem versus latiori, margine externo sinuato, modice inflato, apice 

 spina longiori. Epistomate antice angustiori, truncato, dimiclio latiori, 

 lateribus excisis. Pedibus maxillaribus externis intus parum villosis, sub- 

 tus nuclis. Thorace subovoideo, parum-punctato, lateribus subtilissime 

 granulosis; linea profunda, subsinuata, lateribus divisa, spina laterali 

 acuta; areola plana, paulo latiori, antice posticeque osquo dilatata, 

 Postabdomine thorace subangustiori, fere lasvi, segmentis penultimis 

 angulo externo mutico ; lamina media parte apicali breviori, subangus- 

 tiori, rotundata ; parte basali quadrangulari, antice utrinque bispinosa. 

 Pedibus anticis brevibus, chela modice lata, subdepressa, punctata, sub- 

 tus lsevi, margine interno brevi, recto, paululum serrato ; digitis fere 

 cluplo longioribus, rectis, margine interno costato-lineatis, basi intus 

 subdentatis. Carpo lato, oblique truncato, sublsevi, spina media in- 

 terna, subtus spina solum externa antica valida. Brachio brevi, lasvi, 

 spinis duabus anteapicalibus oblique positis, spinis inferis biseriatis, dua- 

 bus anticis exceptis subnullis. Pedibus tertiis articulo tertio unguicu- 

 lato. Pedibus quintis capitulo basali cylindrico. Pedibus abdominali- 

 bus brevioribus, subcontortis, apice moclo bifidis, partibus cylindricis, 

 crassioribus, asqualibus, parte interna, apice subacuta paulo introrsus 

 curvata, parte externa fusco-cornea, tenuiori, acuta. 



Forma II. differt chela angustiori, crassiori, lseviori ; pedibus abdomi- 

 nalibus, basi articulatis (interdum non articulatis) partibus apicalibus 

 aequalibus, parte externa non fusco cornea. 



Femina differt chelis minoribus ; ventre inter pedes quartos lasvi, 

 annulo obovato, subdepresso, fissura longitudinali dentata, apertura 

 transversali nulla. 



Long. corp. 2.6 ; long. ped. ant. 2.3. 



Ordinarily, long. corp. 1.5 at 2. 



Patria : Lake Oneida ; Lake Superior ; Niagara ; Ogle County, Illi- 

 nois ; Delphi, Indiana ; Rochester, N. Y. 



I have seen many examples. In one abnormal male the third pair 

 of legs are not hooked ; some males have the third joint of the second 

 pair of legs hooked. 



A male type (Forma I.) found by Professor Baircl on Grass River, St. 

 Lawrence County, N. Y., and communicated by Professor Stimpson, is 

 identical with the specimens from Lake Superior. Mr. Girard has seen 

 specimens of this species from Lake Ontario, Garrison Creek, Sackett's 

 Harbor, Four-Mile Creek, Oswego. 



In one abnormal male the first pair of the abdominal legs are not 

 developed, but they have the same shape as those of the females. 



One male, Delphi, Indiana, is larger, long. corp. 3.2 ; ped. ant. 3.1, 

 but very similar. The hands are more developed, as is commonly the 

 case in old males ; the abdominal legs are similar in form, but the pos- 

 terior margin is a little hooked in the middle, and more emarginated 



