04 ASTACID^E. 



Femina differt chelis minoribus ; ventre inter pedes quartos kcvi, an- 

 nulo magno, fere cordiformi, fissura transversa, lata, profunda, margine 

 tumido, antice fisso. 



Variat interdum angulis rostri ad acuminis basin longioribus brevi- 

 spinosis ; rostri interdum angustiori, acumine longiori ; lamina anten- 

 narum rostro longiori. 



Long. 3.2 ; long, antenn. 2.4 ; long. ped. antic. 2.7. 



Patria : Lake Superior ; Lake Winnipeg ; Saskatchavan and Red 

 River, British America, and Toronto, Canada ; Quincy, Illinois ; Daven- 

 port and Burlington, Iowa; Miami River, Day ton, Ohio ; Osage River, 

 Missouri; Sugar River, Wisconsin (Mus. Salem) ; Texas. 



I have seen the male of both forms from Lake Superior anil from 

 Illinois. 



Var. A. 



I have seen many full-grown male (Forma II.) and female examples 

 from the Osage River, Missouri, and male and female from the Miami 

 River, Dayton, Ohio, in the Philadelphia Museum, which I cannot yet 

 separate specifically. The rostrum is smaller anteriorly, the thorax 

 seems not so much dilated and less punctated, the areola is a little 

 smaller ; the fingers are more separated, the exterior more notched at 

 the base interiorly; the carpus is trispinose beneath at the apex, the 

 third spine is between the great middle interior spine and the two or- 

 dinary apical spines ; the legs composing the third pair are not so much 

 hooked, and those of the abdomen are similar to those of the second 

 form described. 



The male (Forma I.) and female from Davenport, Iowa, are in form 

 and specific character doubtless identical with the examples from Lake 

 Superior; but they agree more nearly with the specimens from the 

 Osage River in the form of the rostrum and the greater development 

 of the spines ; the third spine on the carpus is more or less visible. 



It is likewise impossible to separate the males and females from 

 Texas. The rostrum is intermediate, but more similar to the Osage 

 examples; the abdominal legs (Forma I.) are of the typical form; the 

 carpus is trispinose, but in some examples from Lake Superior there is 

 a similar third spine very little developed. One male is larger : Long, 

 corp. 4.1 ; long. ped. antic. 3.7 ; long, chela?, 2.2. In this male the 

 fingers are more elongated. 



The examples from Burlington, Iowa, are similar to the Texas ex- 

 amples. The male has a little hook at the third joint of the second 

 pair of legs, but a similar monstrosity is not very uncommon. Acci- 

 dentally the spines on the rostrum are more or less obliterated. 



Cat. Xo. 11-31, Lake Superior, L. Agassiz. Male Form I. and LI. 

 Fern. Spec. 12.* 



