Classification of the Diplopoda. 291 



great specialization, acquired branched trachea and accessory- 

 feet to subserve copulation at the end of the body, the latter, 

 retaining the tufted tracheee, developed copulatory organs from 

 the appendages of the seventh segment. The Polydesraidge, 

 in possessing comparatively few body-somites, no mandibular 

 cardo, and no promentum in the gnathochilarium, show 

 great approximation to the ancestor of the Chilognatha, and 

 therefore to the ancestor of the Helminthomorpha, and are 

 further shown to be the nearest living representatives of this 

 latter by the conversion of the anterior pair of limbs alone of 

 the seventh segment into copulatory organs and by the reten- 

 tion by these organs of their primitive external position. By 

 possessing but one pair of copulatory organs the Lysiopeta- 

 lidse show relationship with the Polydesmidee ; but by the 

 internal position of these organs and by the presence of a 

 great and variable number of segments, of a mandibular 

 cardo, and of a labial promentum, they show greater rela- 

 tionship with the lulidse. The conversion of the second pair 

 of appendages of the seventh segment into a copulatory 

 organ and the power to retract these within the segment 

 distinguish the lulidge. From the lulidse the Polyzonidge 

 show degeneration by the reduction of the mandibles, and 

 possibly the Chordeumidse by the loss of the foramina repug- 

 natoria. 



To show in a condensed form the views here expressed as 

 to the exact position to be assigned to the different families of 

 the Diplopoda the following classification has been drawn up. 

 But it must be borne in mind that, except in that greater 

 value has been given to some groups and less to others, this 

 classification, so far as concerns the relationship of the Poly- 

 desmidge, Lysiopetalidai, lulidse, and Chordeumidas, is almost 

 identical with that formulated by Dr. Berlese in 1886, and, 

 so far as concerns the position of the Glomeridee, Polyxenidse, 

 and Polyzonidas, is little more than a modification of that sug- 

 gested by M. de Saussure in 1872. That the ideas of this 

 latter naturalist have received so little attention from subse- 

 quent writers is a matter to me of no little surprise. 



It will be observed that no place has been assigned to the 

 numerous extinct forms of Diplopoda. My excuse for the 

 omission must be my ignorance of the structure of these 

 fossils. Indeed, the knowledge possessed even by those who 

 have especially studied this branch of the subject is, from the 

 nature of things, but limited, and its extent may be perhaps 

 to a certain degree estimated by the fact that Mr. Scudder 

 has recently confessed, with an honesty which disarms com- 

 ment, that certain portions of an organism described by him 



