12 



TEXT-BOOK OF ENTOMOLOGY 



dens 



- After Latzei.- 



inclined to do, with the insects. There are two sub-classes of 



myriopods, differing in such important respects that by Pocock l and 



by Kingsley they are regarded as independent classes, each equiva- 



lent to the insects. 



Of these the most primitive are the Diplopoda (Chilognatha), 



represented by the galley-worms (Julus, etc.). 



In the typical Diplopoda the head consists of 

 three segments, a preoral or antennal, and two post- 

 oral, there being two pairs of jaw-like appendages, 

 which, though in a broad morphological sense homo- 

 logues of the mandibles and first maxillae of insects, 

 are quite unlike them in details. 



As we have previously stated, 2 the so-called 

 " mandibles " of diplopods are entirely different 

 from those of insects, since they appear to be 2- 

 5. Mandi or 3-jointed, the terminal joint being 2-lobed, thus 

 resembling the maxillae rather than the mandibles 

 of insects, which consist of but a single piece or 

 ; m, muscle! joint, probably the homologue of the galea or molar 

 j oint o f the diplopod protomala. The mandible of 



the Julidse (Fig. 5, Julus 



molybdinus), Lysiopetalidse, 



and Polydesmidae consists of 



three joints; viz. a basal piece 



or cardo, a stipes, and the mala 



mandibularis, which supports 



two lobes analogous to the 



galea and lacinia of the maxilla 



of an insect. There is an ap- 



proach, as we shall see, i-n the 



mandible of Copris, to that of 



T -i . -, i i. 



tile dUllClya, L>Ut l 



l j-l l^^v, nfi'vi 



general tlie lacinia is wanting, 



^1 flio TQ-iv f>nni<if<: nf but a 



and tlie ]aw consists at a 



single piece. 



The deutomalae (gnathochilarium), or second pair of diplopod jaws, 

 are analogous to the labium or second maxillae of insects, forming a 

 flattened, plate-like under-lip, constituting the floor of the mouth 

 (Fig. 6). This pair of appendages needs farther study, especially 

 in the late embryo, before it can be fully understood. So far as 



FIG. 6 . Under lip or deutomala of Scoter jies 

 copei . h,^, hypostoma or mentum ; lam. lab, 

 lamina labialia ; xti/>. e, stipes exterior: with the 



,.,,,, ext ,, n ,, r <;/. e , and maieiia interior 



( " 1 " 1 '> ""' sti '' es interior . with the nialiiU-lhi ; 



an(lth( . | a i, j( .|| a (hypophurynx orv..m uatiu with its 



1 Zool. Anzeiser, xvi, 1893, pp. 271-5. 



2 On the morphology of the Myriopoda, Proc. Amer. Phil. Soc. 1883, pp. 197-209. 



