MILLIPEDES 



3177 



composed of only six segments, the basal of which is much enlarged. There are no 

 true eyes. Glomeridesmus, the typical genus, is known from two species, found 

 respectively in New Granada and in St. Vincent; the other genus, Zephroniodes- 

 mus, occurring in Sumatra. None of the species exceed a quarter of an inch in 

 length. 



In the Helminthomorpha, or worm-like millipedes, which comprise the majority 

 of the species, the body is composed of from nineteen to over ninety segments, is 

 usually elongate and slender, and capable of .being spirally coiled. The character- 

 istics by which this group may be distinguished from the two preceding are that 

 the last tergal plate forms a complete ring, inclosing the pair of valves and sternum, 

 and that the tracheal plates take the form of two median sternal pieces, to which 

 the legs are directly articulated. Moreover, the pleural scutes, although sometimes 

 free, are less distinct than in the preceding groups. The order is divided into the 

 suborders Colobognatha, Chordeumoidea, Callipodoidea, luloidea, and Polydes- 

 moidea. In the first of these the mandibles have undergone great degeneration, 

 and in the most modified forms (Siphonophora) , the lower edge of the head (labrum) 

 and the lower lip (gnathochilarium) are together produced into a long, piercing 

 snout. The pedal laminae, or sterna, are always free and movable, as are rarely the 

 pleurae. The secreting pores are present on all the segments, with the exception of 

 the first four and the last; the parts of the segments around the pores being some- 

 times produced into wide plate- or rod-like processes covering the legs. The body 

 segments vary in number from about thirty to over seventy, although the largest 

 members of this group seldom exceed an inch in length, and are generally shorter. 

 These millipedes occur in the tropical countries of both hemispheres, one form 

 (Polyzonium germanicum) extending into Central Europe. In the Chordeumoidea 

 there are no excretory pores, but each segment bears six symmetrically-arranged 

 bristles. There are usually either thirty or thirty-two body segments; the pedal 

 laminae are always free, and often the tergal plate is keeled, or furnished with a 

 large lateral proc- 



ess on each side. 

 There is a pair of 

 eyes on the head, 

 and the jaws are 

 normally d e v e 1 - 

 oped. 



The luloidea, 

 which is the largest 

 suborder of the 

 worm-like m i 1 1 i - 

 pedes, contains 

 families which may MILLIPEDE, lulus sabulosus (enlarged twice) . 



b e distinguished 



from the last group by having the pedal laminae united to the terga. Some of the 

 tropical species reach six inches or more in length, and are the largest millipedes. 

 Of the families, the Spirostreptida are spread over all tropical countries, but scarcely 



