much more rigid than in the Chilopods, from the close conjunction, or often imbrication, of the segments, and the inflexibility of the segments themselves, caused by the density and thickness of the scuta aud sterna and the absence of lateral membranes. For this reason the Diplopoda possess but little or none of that power of raising and twisting the body, which is so annoying to the collector of tropical Scolopendra. The poorly developed nervous system and organs of special sense, the short weak legs, and the weak muscular and large intestinal development, all point to the vegetable nature of the food of this order and the associated sluggish habits, which indications the total absence of offensive armature confirms.
M. Brandt (Recueil) divided the Myriapoda into Myriapoda manducentia and Myriapoda sugentia. The former comprises all those which are provided with mandibles or jaws for seizing or devouring food. The latter, the few centipedes which have the different pieces about the mouth so united and consolidated as to form a tubule, fitted for the ingestion of liquid food. Although this classification has emanated from such an authority, yet it seems apparent that it does not agree with nature, and must be abandoned. Still, it has seemed to me that in doing this Mr. Newport and others have not allowed these characters the weight that they deserve. Mr. Gray does not even allow them generic force, if his classification (Cyclop. Anat. and Physiol., art. Myriap.) is to be trusted. Or was he entirely ignorant of their existence! Newport gives to them a family significance.
The different structure of the mouth, and the consequent different food and habits of living, although not sufficient to stand in competition with the characters separating the Chilopoda and Diplopoda, are still of higher import than any other differences in the latter order. I have therefore divided the Diplopoda into two suborders, the Chilognatha and Sugentia, retaining old names, but giving new significance to them. The minor characters have seemed to me to confirm this, and to indicate that it is coincident with the plan on which the Myriapoda have been created. M. Brandt (Recueil, p. 26) divides the Chilopoda into the Schizotarsia and Holotarsia. These appear to constitute natural sub-orders, and are consequently here retained as such.
There has been a great difference of opinion amongst naturalists as to the rank of the Myriapoda, and the position which they occupy amongst the articulata. Mr. Brandt, Gervais, Dana, and others consider them as nothing more than an order of the class Insecta; Le Conte (Class Coleop. N. Am. Introd., p. vii) considers them as a subclass of the class Insecta; whilst Leach, Latreille, Newport, T. Rymer Jones, &c., grant to them the rank of a class. The latter gentlemen differ, however, as to their position in the zoological plan. Mr. Newport places them just above the Vermes, and this seems to be their natural position.
There is doubtless a good deal of resemblance between a hexapod larva and a myriapod,
