166 KANSAS UNIVERSITY SCIENCE BULLETIN. 



satisfactorily solved, but the observations have indicated that 

 the species are nocturnal in their habits, and in some cases 

 may leave the burrows and forage for food, or wait at the 

 mouth for anything that may come within reach. That the 

 animals may live for long periods with but little food is known. 



In addition to the above-mentioned species, besides the bur- 

 rowing in the banks or bed of the streams, as has been noted for 

 C. hartonii, C. propinquus , and C. sloanii, there ai'e doubtless 

 others which burrow extensivel}^ when conditions demand it. 

 Lonnberg sometimes found C. fallax and C. allevi "digging 

 holes on the shore at low water." Schufeldt figures the chim- 

 ney of C. bartonii robustus ; C. virilis is reported almost exclu- 

 sively from streams and lakes, but has sometimes been found 

 with C. immunis, almost exclusively a stagnant-pond species, 

 and when in such localities it must burrow, as do forms charac- 

 teristic of such localities. Faxon reports C. blandingii from 

 Texas with the label name of "burrowing crab," a fact which 

 is suggestive at least. 



From the data now at hand, it certainly seems safe to conclude 

 that the burrowing habit has been adopted as a means of living 

 through an unfavorable period, and that in some species this 

 method of life has been adopted as the almost exclusive one, 

 while all the other advantages of this habit of life, if there 

 are any, are entirely secondary.''^ The burrowing species are to 

 be regarded as the most specialized of the genus. 



Exuviation. On the process itself nothing of particular 

 value has appeared, and even if observations were complete, 



granule, and between these granules a large number of tiny grooves are seen. The posterior 

 margin of the cervical groove is armed with a dense row of setae. (See fig. I.) It seems prob- 

 able that these features stand in connection with some biological peculiarities of these cray- 

 fishes. The structure of the carapace on the branchial chamber seems to be apt to retain the 

 humidity longer on this place than if it were smooth, and this might be of use if the crayfishes 

 should make any excursions on dry land. The inner surface of the carapace covering the bran- 

 chial chamber is also very densely hairy, which would also serve the .>-ame purpose — to retain 

 the water. The armature of the cervical groove would help to carry water (rain?) from the 

 back 1o the anterior branchial opening along the cervical groove." Of ('. aNeni and ('.foliar, 

 which he sometimes found burrowing at considerable distance from water, he says: "The 

 inner side of the carapace covering the branchial chamber of these Cambari was also very 

 hairy; so this adaptation seems to be common to several crayfishes with similar habits." 

 Whether the structure of the branchial chamber is to be interpreted as has been done by Lonn- 

 berg is open to doubt. Neither of the species of Cambarim to which he refers is known to be 

 typical burrowing species, and, while I have satis-fied myself of the hairiness of the branchi- 

 ostegite of ( '. cji urilis and ('. h)imu)ns, I am not convinced that it is any more so than in forms 

 which do not live under the same conditions, and, in case the adaptation is of the nature sug- 

 gested, this would be supposed to be the case. The function suggested for the cervical groove 

 requires no comment. 



31. This conclusion is supported by what is known concerningthe behavior of the burrowing 

 species of other genera of the Astacidae. The habits of I'limsinruy, as described by Faxon ('98) 

 and Lonnberg ('98) seem very similar to those of certain species of Cnintxirns, and indicate an 

 extension of the territory habitable by the species, just as we find in C. c/iogoics, (\ grncilis, 

 '.'. ?W(/H'/«/s, and others. The similarity of habits of ' '/i^-op.s liicorinottix and its adaptation 

 to life under very adverse conditions of environment are well seen from the description of its 

 habits as quoted by Faxon ('98). 



