The Craspedosomatidae of North America. 11 



In the Craspedomatidse, however, the dorsal and ventral por- 

 tions of the segments differ less in length, and although the pedal 

 laminae have no chitinized connection with the pleurae, the body 

 is not coiled in a close spiral. Even when tightlj^ contracted in 

 alcohol, Trichopetalum and its allies are able to do little more 

 than form a circle, a position of doubtful use as a means of de- 

 fense, especially when compared with the close spirals which lu- 

 lidse assume. The Craspedosomatidae lack, besides, the strong 

 exo-skeleton and repugnatorial secretion of the other families, so 

 that for them coiling up would not have much advantage as a 

 means of defense. 



As might be inferred from the preceding statements the in- 

 stinct of feigning death is not developed in Craspedosomatidae. 

 While they are able the3" attempt to run away, but if held in the 

 hand the heat and drier atmosphere are soon fatal. This was no- 

 ticed especially in Underwoodia polygama. If held in the hand 

 and exposed to sunlight they were soon unable to run in the 

 ordinary way, wriggled convulsively a few times and died. This 

 would happen in a minute or two, while the specimen was being 

 examined with a lens to determine the sex. In such cases care 

 was taken to see whether the animals would recover, but the}' did 

 not do so. 



Individuals of Trichopetalum are also of very delicate organi- 

 zation. They will not endure captivity to any such extent as 

 other Chilognatha, and will speedily die under conditions appar- 

 ently favorable to the other families. Dryness of the atmos- 

 phere is quickly fatal, and the animals seem to suffer if the venti- 

 lation is insufficient, even though the moisture is adequate. 



On the other hand, it should be mentioned that a specimen of 

 Gonotyla fischeri was found running about on a log one morning 

 in February, when the ground was frozen and the cold severe 

 enough to have covered with ice-cr3'-stals both the ground and 

 the under side of the log. Such ability to withstand the cold ap- 

 peared \Qvy strange at the time, and on investigation it was found 

 that beetles and spiders under the log were incapable of motion, 

 though they recovered after being warmed in the hand. The 

 Conotyla was not, however, under the log, but on the upper side 

 of it, apparently quite as lively and vigorous as during the 

 warmer parts of the year, showing that he had been able to with- 

 stand the cold of the Februar}- night and either keep lively 



