JOURNAL 



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OF Till-. 



ACADEMY OF NATURAL SCIENCES 



<) V I'll I LA DEL I'll I A 





Art. I. — On the Qhilojxxln <>/ Xorth America, with a catalogue of all tin specimens in the 



Collection of flu Smithsonian Institution* 



.By Horatio C. Wood, Jr. 



The body among the Chilopoda is composed of a variable number of segments, each 

 of which is formed by the junction of two subsegments, one of them being very much 

 atrophied and without appendages. Each subsegment is divisible into a dorsal and 

 ventral portion ; the former comprising the scutum or dorsal shield and the superior 

 portion of the sides with the spiracles, the latter the sternum or ventral shield and 

 the inferior portion of the sides with the legs. The scutum is originally formed by 

 the conjunction of two central and two lateral pieces, the former we have called the 

 primitive scuta, the latter are the episcuta of Newport. The sternum is in like man- 



* It will be seen that the principal portion of our material cosnists of the collection of the Smithsonian In- 

 stitution, which was placed at our disposal, in accordance with the liberal constitution of that Institution. 

 And we are especially indebted to Prof. Baird for many facilities afforded us by him. We would also acknow- 

 ledge our obligation to Samuel II. Scndder, Esq., of Cambridge, for the trouble incurred in sending the 

 specimens belonging to the Museum of Comparative Zoology, kindly loaned us by Prof. Agassiz. 



We doubt not there are etill unknown species scattered throughout the country, specimens of which we have 

 been unable to obtain. We think that they will more especially be found among the Geophilida;. And if 

 Naturalists would send us suites from their own neighborhoods, we would be very happy to label and return 

 them, retaining duplicate specimens of forms unknown to us. 



The West Indies, of course, are not included in our domain. Mexico forms geographically a portion of N- 

 America, but its fauna is much more closely allied to that of S. America. 

 VOL. v 



