The GrasjDedosomatidse of North America. 31 



cies, but none of these seem to have the second pair of feet of the 

 se\'enth segment with more than one joint, a club-shaped, perpen- 

 dicular structure, thus differing distinctly from the more closely 

 allied of the American genera : Conotyla, Trichopetalum, Sco- 

 terpes and Zygonopus. 



Chordeuma, C L. Koch. Latzel suggested the possibility that 

 Trichopetalum juloides Harger would be placed here. Charac- 

 ters drawn from the genitalia, gnathochilarium and secondary 

 sexual characters give ample reason for holding the American 

 form distinct and erecting a new genus for its reception. 



Striaria has been recognized as the type of a distinct family. 



Cryptotrichus Packard, is replaced b}^ Cleidogona. 



In Austro-Hungarj' are found two genera of Craspedosomatidse 

 with broad lateral carinse, Atractostoma closel}' resembling the 

 Polydesmidse, and Rhiscosoma the Polyzonidai. Latzel failed to 

 find bristles on an immature specimen of Rhiscosoma, but as 

 other individuals referred to the same species had bristles we 

 have not lost confidence that the bristles are universal in Chor- 

 deumidaj, more especially since finding them on Pseudotremia 

 where Latzel asserted their non-existence. 



Humbert and Saussure * proposed to include all the species of 

 this family as here constituted under Craspedosoma, divided into 

 two subgenera, Craspedosoma, in a stricter sense, and Chordeuma, 

 alleging that in Craspedosoma there is a promentum distinct 

 from the mentum, while in Chordeuma the mentum is entire, and 

 rounded anteriorl3^ Latzel takes no notice of this distinction, 

 and does not describe or figure' the gnathochilarium of the only 

 species, Chordeuma sylvestre Koch, leaving the implication, how- 

 ever, that there is no important difference in this respect, since 

 the family description states that the promentum is " deutlich 

 entwickelt, dreieckig." 



Meinert united Craspedosoma with Polydesmus, but his reasons 

 for so doing do not seem to include a knowledge of the more 

 fundamental relationship, and were matters of generic descriptions 

 based on external characters. 



Dissection is an absolute necessity in studying the genitalia of 

 the smaller forms, and the greatest caution must be exercised, 

 for the different views of the same irregularly shaped genitalium 

 will look like entirely different structures. The small size of the 



* Etudes sur les Myriapodes, p. 59. 



