594 CLASS III. MYRIAPODA. 



bert and S., Mexico. Cryptodesmus Ptrs., Columbia. Platyrhachis C. 

 Koch, Tropics except Afr. Polydesmus Latr., cosmopolitan. Strongy- 

 losoma Brdt., cosmopolitan. Brachydesmus Heller, 19 segments, Palaearctic. 



The following three families are included by Silvestri with the Helmintho- 

 morpha, by Latzel they are united in a distinct sub-order, the Colobognatha. 

 They are small Diplopods with numerous segments (30-100), variable 

 in the same species. Eyes present or absent. The small triangular head 

 is elongated into a longer or shorter proboscis, and the mouth parts appear 

 to be modified for suction, though it is doubtful if any, except those with 

 long proboscis, are suctorial. The mandibles are small and the maxillae 

 degenerate or absent. 3rd segment and two last apodal, 1st and 2nd 

 with one pair of legs. Foramina repugnatoria present in two lateral rows. 

 Copulatory appendages simple and in two pairs on the 7th segment, which 

 is apodal. They live in damp places. Europe, Asia, America, Africa. 



Fam. 5. Siphonophoridae. Head pyriform, produced into longish 

 rostrum. Eyes and mandibles absent. Maxillae as a single lamina 

 coalesced with labrum to form rostrum. Siphonorhinus Pocock, Malaya. 

 Siphonophora Brdt., tropics. 



Fam. 6. Polyzonidae. Head with short rostrum and eyes. Mandibles 

 two-jointed. 2nd maxillae represented by a triangular plate. Poly- 

 zonium Brdt., palaearctic and nearctic. 



Fam. 7. Platydesmidae.* Head small and spherical ; eyes present or 

 absent. Mandibles with 2 joints ; maxillae as distinct gnathochilarium 

 more or less reduced, inframaxilla undivided and long. Tergites with 

 lateral keels. Segments numerous. Platydesmus Lucas, N. and C. 

 America. Dolistenus Fanzago, Mediterranean. 



Order CHILOPODA.t 



Opisthogoneates with a head bearing three pairs of jaws (mandibles 

 and two pairs of maxillae) , a pair of poison claws (maxillipeds) on 

 the first body segment, and with a body consisting of numerous seg- 

 ments, all of which, except the last two, bear one pair of legs. The 

 gonad is dorsal to the gut and opens on the penultimate body- 

 segment. 



The body is flattened dorso-ventrally, and the legs are set 

 far apart at the sides of the ventral surface. The chitinous. 

 covering is either very poor in, or completely free from calcareous 

 salts, and in the course of life is frequently shed. The head, 



* F. G. Sinclair, Q.J.M.S., 49, 1905, p. 507. 



f G. Newport, Monograph of the class Myriopoda, order Chilopoda,. 

 Linn. Trans., 19, 1845. E. Metschnikoff, Embryologisches iiber Geophilus, 

 Z.f.w.Z., 25, 1875. N. Zograf, Anatomie v. Lithobius forficatus (Russian),. 

 Schrift. d. Gesell. d. Freunde der Naturwiss, etc., Moscow, 1880. E. Haase, 

 Schlesiens Chilopoden, Breslau, 1880-81. Id., Das Respirationssystem 

 der Symphylen u. Chilopoden, Schneider's Zool. Beitrdge, 1, 1885. R. 

 Latzel, op. cit. C. Herbst, Beitrage zur Kenntniss der Chilopoden 

 Bibl. Zool., 9, 1891. O. Duboscq, Rech. sur les Chilopodes, Arch. Zool. 

 Exp., 1898. R. Heymons, op. cit. on p. 314. C. Verhoeff , Chilopoden in 

 Bronrfs Thierreich, 1902-7. 



