166 S. H. Scudder— Diversity of Type in ancient Myru< ril h. 



poor preservation in the only specimen in which they have 

 been seen prevents any thing more than the mere statement of 

 the following difference : while the legs of Chilopoda are inva- 

 riably horny, slender, adapted to wide extension and rapid 

 those of Palseocampa are fleshy, or at best subco- 

 :ry stout and conical, certainly incapable of rapid 

 and serving rather as props. 



These differences, which underlie every part of the body thai 

 is preserved in Paleeocampa, show that while the general 

 ee of grand features compels us to look upon Pakeo- 

 campa as a precursor of the Chilopoda, we must separate it 

 from them in the same way as we separate the Archipolypoda 

 from the Diplopoda. For such a group the name of Proto- 

 syngnatha is proposed, indicating its ancestral relations to the 

 chilopods, or Syngnatha, as they were called by Latreille. 



There are, however, two aberrant groups of living animals 

 more or less closely related to myriapods, and placed with 

 them by some authors, with which also we should compare 

 a. The first of these is Peripatus, our knowledge 

 of which has been so much increased of late years, and espe- 

 cially by the researches of Moseley. 



In external appearance Peripatus resembles au annelid, but 

 is furnished with a pair of long, jointed antennae, and with 

 numerous fleshy, tapering legs, each armed at tip by a pair of 

 claws; the legs, set wide apart, are obscurely jointed, the joints 

 being perceptible only at the extreme tip and on the apical half 

 of the inner side, above which are the large elongated openings 

 into the nephridia. The entire body is of a leathery texture 

 with no external sign of segments, or of the separation of the 

 head from the rest of the body, except the appendages: 

 namely, the legs, the nephridia opening on the legs, and the 

 ordinary appendages of the head. The°same is true when the 

 structure of the body is examined, for neither in the 

 ►n of the muscles nor of the tracheal apparatus does it 

 appear that one could judge whether a pair of legs represented 

 one or more segments of the body ; even in the nervous sys- 

 tem it is only indicated by a small ganglionic swelling next 

 each pair of legs. The tracheae are like extended cutaneous 

 glands, independent of one another, and scattered over the 

 body, and the longitudinal muscles show no regular segmental 

 breaks. This weakness of segment;!.! divisions' U nowhere par- 

 alleled among hexapods. arachnids or myriapods. and is an 

 ■si of very low organization among arthropods gen- 

 erally. The number of legs indicates from 15 to 35 segments 

 in the body, according to the species. The first pair, as they 

 are developed in the adult, ire r i icr . d.-.— a- k-s. and are sit- 

 uated (in the specimens I have ■ - i American 



