10 The Graspedosomatidse of North America. 



Notes on Habits and Structure. 



The habits of living Craspedosomaticlffi show considerable differ- 

 ence from those of other families, and emphasize the importance 

 of some structural characters which have, we think, not received 

 proper weight in classification. 



Reference is made chiefly to Trichopetalum,* which on account 

 of its abundance, small size and transparent exo-skeleton is well 

 suited for observation. But so much alike are all the members 

 of this family, that there is probably little difference with regard 

 to considerations of habits or structure, with the exception of 

 lack of ej'es in cave forms. 



In central New York Trichopetalum is one of the most common 

 and generally distributed of Diplopoda, though liable to be over- 

 looked on account of its small size. Like the other members of 

 this family it inhabits rather wet places, but does not seem par- 

 ticular in other respects, living among mosses and rotting leaves, 

 and under sticks and pieces of bark. 



When undisturbed the gait of Trichopetalum is quite leisurely, 

 but when frightened it never attempts to protect itself by coiling 

 up, relying on its powers of flight. This course is warranted by 

 the fact that the Craspedosomatidse are more fleet of foot than 

 other Chilognatha, though some species of lulidse are able to 

 progress at a very respectable pace. It is also noteworthy that 

 the fleeter species of lulidae (Paraiulus) are not inclined to coil 

 up when frightened, but attempt to run, and even when captured 

 and held they do not at first employ the ruse of coiling up and 

 feigning death, but attempt to escape by vigorous wriggling. 

 All lulidpe seem, however, to have the power of coiling up, and 

 will sooner or later exercise it for protection. 



The ability to coil up depends on a certain form and structure 

 of the segments. The dorsal part must be longer than the ven- 

 tral, and the amount one segment overlaps the next must be 

 greater in the form that is able to coil up. There is also necessi- 

 tated a larger amount of flexible integument between the seg- 

 ments. 



The lulidse manifest all these characters, even to the flattening 

 of the pedal lamina and the basal joints of the legs ; other Chilog- 

 natha have them, usually in a less degree. 



* The species described in this paper as Trichopetalum album. 



