ORTMANN: THE CKAWFISHES OF THE STATE OF PENNSYLVANIA 389 



TJtc shape of titc carapace i.s similar to that of ('. bartoni, but, in old specimens, 

 appears slightly more depressed on account of the wider hepatic and branchial re- 

 gions ; G :H :B = 1 : 1.3 to 1.5: 1.5 to 1.7. 



The rostrum (Plate XXXIX, Figs. 2f/ and 2/1) is markedly different from the 

 typical form, narrower, more tapering, and with a longer acumen ; the upper sur- 

 face is slightly concave. The shape is rather variable. In young specimens of the 

 typical ('. bartoni the rostrum often approaches the form of C. bartoni robustns, but 

 on the other hand young specimens of the latter have a narrower rostrum than the 

 Ibinier. (( "ompare Plate XXXIX, Fig. If and 2//). In many cases the rostrum of the 

 variety is not longer than in the typical form, but in others it surpasses it, reaching 

 to the middle, or even almost to the end of the third joint of the peduncle of the 

 antennula, or to the base or almost to the middle of the fifth joint of the peduncle 

 of the antenna. 



Areola similar to that of the typical form, but with a larger number of rows of 

 punctures (4-6), whicli is due to the punctures being more crowded, not only on 

 the areola, but on the whole carapace. 



The carapace is often provided with small and sharp lateral spines; the}' are 

 sometimes obsolete, or replaced by tubercles, or even entirely absent. 



Anfoinal scale generally slightly wider than in the typical form, and slightly 

 longer. 



Antennal flagellurii not differing greatly from that of the typical form, and quite 

 varial)le in length. Tliere are a few cases where it reaches to the end of the telson, 

 and even slightly beyond, thus surpassing any case known in C. bartoni. 



The first j)ereio2)ods (Plate XL, Fig. 3), display remarkable and important differ- 

 ences from the typical form. The hand has nearly the same shape, but the fiugei-s 

 are less gaping, and meet all along their edges even in individuals of a considerable 

 size (retention of juvenile character); it is only in very large specimens that they 

 are distinctly gaping, but less so than in much smaller individuals of C. bartoni. 

 Tlie .sculpture of the hand is much more strongly developed. The inner margin of 

 the hand has a distinct and regular double row of tubercle-s. This double row is a 

 very important character, and is noticeable in specimens from the size of about 30 

 nun. ujjward. In very young individuals it is ob.solete, and becomes more and 

 more distinct with advancing age. Every specimen at hand, without excep- 

 tion, possesses this character, when the cheUe are normally developed ; but it nuist 

 be mentioned that in regenerated chela?, which are always recognizable by their 

 shape, this double row is sometimes indistinct or irregular. Further, there is a tri- 

 angular depression both on the upper and lower side of the hand at the base of the 



