MILLIPEDES 17 



13 tergal plates of which the second is enormously expanded at 

 the sides while the last forms a rounded shield which fits against 

 it and conceals the head when the animals are coiled up. In the 

 males the last, or last two pairs of legs form claspers and the basal 

 segments of the last pair are modified as sperm carriers. The 

 family Glomeridae contains the common British pill-millipede, 

 and a number of other small species found in Europe, America and 

 Asia; while the Sphaerotheriidae have a southern distribution and 

 occur in South Africa, Madagascar, southern Asia and Australasia. 

 Some of them are of large size, surpassing a golf ball when rolled 



up. 



The millipedes of the order Limacomorpha resemble the Onis- 

 comorpha in general structure but are of small size, measuring 

 not more than about one quarter of an inch in length. The two 

 families Glomeridesmidae and Zephroniodesmidae inhabit tropical 

 America and tropical Asia respectively: nothing is known of their 

 biology. 



The third order, Colobognatha, and those that follow differ 

 from the two preceding in that the last tergal plate encircles the 

 anus which is closed below by a sternite and laterally by a pair of 

 valves. The last pair of legs is unmodified in the male. The body 

 is long, spirally coiled when at rest and contains a large and 

 variable number of tergal plates which carry repugnatorial glands 

 usually opening on tubercles or larger keel-like outgrowths. This 

 order is found in all the warmer countries of the world where it is 

 represented by several families, such as the Pseudodesmidae, 

 Platydesmidae, Polyzoniidae and Siphonophoridae, which ex- 

 hibit a progressive reduction of the mandibles. In Siphonophora 

 spp. the mouth opens at the tip of a long, pointed, sucking and 

 piercing beak formed by the labrum and gnathochilarium, the 

 mandibles within it being greatly reduced. The only British mem- 

 ber of the Colobognatha is Polyzonium germanicum which has been 

 found on the chalk downs of Kent and Surrey. It is a bizarre form 

 with semi-suctorial mouthparts and can be readily identified in 

 collections from the fact that when preserved in alcohol it is convex 

 dorsally and flat or concave ventrally. 



The members of the order Ascospermophora have 26 to 32 

 segments. The tergal plates coalesce with the pleura, but the 



B S.S.C.M. 



