388 MEMOIRS OF THE CARNEGIE MUSEUM 



ten young ones, ready to leave the mother, (very hkel}' a number had left already 

 when the mother was captured). It has on the ischiopodite of the left third perei- 

 opod the copulatory hook of the male ; this hook is not small or rudimentary, but 

 strong, and similar to the hook as found in the male of the fii'st form. The ischi- 

 opodite of the corresponding right pereiopod has no trace of this hook. 



2. A specimen, 48 mm. long, was found in P^ern Hollow, Pittslmrgh.'Novemljer, 

 22, 11)05, (Cat. No. 74. 681). whicli externally (in the sliape of the claws) looks like 

 a female, but shows very indistinctly the sexual openings of the male, and no traces 

 of those of the female. Ft also has the first plecjpods of the male of the second form, 

 but the second pleopods are built according to the female type. Further, it lacks 

 entirely the hooks of the third jiereiopods. and has a distinct female annulus, of 

 juvenile type. 



This case does not correspond exactly to any of those de.sci'ibed previously. It 

 resembles to a certain degree one of the cases in C. ohscurus described above (No. 3), 

 with the exception that here the fii'st pleopods are of the type of the male of the 

 second form, and that the second pleopods are not of the male, but of the female type. 



4a. Cambarus (Bartonius) iurtoni robustus (Girard). 

 (Plate B, Fig. 2. Plate XXXIX, Fig. 2</ and 2h. Plate XL, Fig. 3.) 



Cmiihanis rabustiis Girard, 1852, p. 90 ; Hagen, 1870, p. t-0, PI. 3, f. 167 ; Smitli 1874, p. 639 ; Faxon, 18846, p. 143. 

 Cambarus harloni rohustns Faxon 1885a, p. (il ; Faxon, 18856, p. 358; Underwood, 1886, p. 367; Faxon, 1890, p. 622; 



Faxon, 1H98, p. 649 ; Osburn & Williamson, 1898, p. 21 ; Williamson, 1899, p. 20, 47 ; Hay, 1899, p 959, 966 ; 



Williamson, 1901, p. II ; Ortmann, 19U5n, p. 391 ; Ortmann, 19056, p. 135. 

 Cambarus harloni Williamson, 1905, p. 310. 



The differential characters of this form are the following : 



Bodij robust, attaining decidedly a more considerable .size than the typical har- 

 toiri. The largest individuals at hand are a male, first form, fi-oin Spartansburg, 

 ( "rawford County, measuring about 98 mm. (estimated, since rostrum is damaged) ; 

 a female from Squaw Run, Allegheny County, measuring 94 mm. and a male, 

 second form, from Puketta Creek, Allegheny Count}^ (A. Kcenig coll.), measuring 

 101 nun. I have quite a number of males (of the first and second form) and of 

 females over 90 mm. long. It is also remarkable that specimens of this variety, of 

 a considerable size (60 to 70 mm.) display characters which are distinctly juvenile, 

 showing no tendency on the part of the chelce to attain a large size. This tendency 

 is also evidenced by the fact that the smallest males of the first form at hand are two 

 individuals measuring 72 mm. (Union ( 'ity and Plulton). From Oberlin, Ohio, I 

 have .seen a male of the fir.st form, 71 mm. long, while the minimum size of sexually 

 ripe males of the typical form is 50 mm. for western, and 49 mm. for eastern 

 Pennsylvania. 



