244 CLASS MYRIAPODA. 



again there is a similar but less marked degradation in value as we go from the higher to 

 the lower order. There is very little alteration in the segments of the body in the Chilo- 

 poda. They are all formed after one common type ; more or less parallelopipedal, with a 

 solid sternum below and scutum above separated by membranous sides, which give origin 

 to the appendages. The only important aberrations from this are the occasional fusion of 

 two scuta into one, and at times a slight development of the atrophied subsegment. Not 

 so in the Chilognatha ; here there are three distinct types of form and composition of the 

 segments. Now each of these is peculiar to one of the three divisions indicated, strongly 

 corroborating their claims to rank as suborders. 



There is one imperfection in my knowledge of the subject which I recognize and would 

 guard against. I have never seen any of the species of the Polyxenidrc, and have not 

 read a sufficiently accurate description of them and their anatomy to be able to assign 

 their place ; yet is it questionable but that they belong in one of the three suborders ? 

 There seems to be no room for a fourth division. 



CLASS MYRIAPODA. 



ORD. I. SYNGNATHA.* 



Caput segmentis duobus distinctis compositum. Corporis segmenta subsegmenta unica 

 efformata, singula pedum par unicum instructa. Organorum sexualium apertura ad ex- 

 tremitatem posteriorem. 



Ord. Syngnatha, Leach, Linn. Trans., vol. xi, 1815, p. 381.f 



Ord. Chilopoda, Latreille, (lours D'Entomologie, 1831, p. 175, et aactores. 



* Although it would seem much better to retain the name of Chilopoda, it having been so universally adopted, 

 yet the prior appellation must, have the preference. T have used Chilopoda all through this memoir through igno- 

 rance of the priority of Syngnatha. 



f -Mr. Newport states (Linn. Trans., vol. six, p. 273) that the name Syngnatha was originally proposed by M. 

 Latreille, and adopted by Dr. Leach. Dr. Leach, however, gives the name as his own (loc. «'/.), and T have not 

 been able to 6nd it in any of the works of Latreille at my command. Mr. Newport does not refer to the place 

 where the lattci uses it. 



