12 



TEXT-BOOK OF ENTOMOLOGY 



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- 

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



ble of Jnlus : I, laci- , -, . ,, .,, 



nia; g, galea, p, dens resembling the maxillae rather than the mandibles 



mandibularis : ma, / r i, . c > > 



"mala"; it, lamina or insects, which consist of but a single piece or 

 c?cardo' ; m, muscle! joint, probably the homologue of the galea or molar 

 joint of the diplopod protomala. The mandible of 

 the Julidse (Fig. 5, Julus 

 molybdinus), Lysiopetalidae, 

 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, in the 

 mandible of Copris, to that of 



thp Tnlirlv hilt in inppf<s in FIG. 6. Tinder lip or deutomala of Scott rpes 



tne JU KISS, t 1 cop?i . hyf> hypo?toma men tum; law.lab, 



crpnprnl thp lipinia is wan finer lamina labialis ; stip. e, stipes exterior: with the 



'" Un S> maiella exterior (mal. e) and malella interior 



and the law Consists Of but a (m f-, *}'** fP es interior with the malulella ; 



J and the labiella (hypopharynx of Vom Rath) with its 



single piece. stilus {stil -^ 



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 



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



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



