SIBOGLINUM CEYLONICUM 303 



(Fig. ММ133Д B). The boundary between the mesosoma and metasoma is 

 arched forward on the dorsal side and forms a small median nick on the 

 ventral side (Fig. MM 1335). 



The metameric part of the trunk is moderately long. The dorsal ciliated 

 band begins at the front edge of the metasoma (Fig. MM 133^). The ventral 

 blood vessel can often be seen along the bottom of the well-marked ventral 

 sulcus (Fig. MM133Z)). The papillae at the sides are comparatively large and 

 rounded, and lie close together. Each encloses a single pyriform gland which 

 is visible through the skin. On many papillae there is a tiny cuticular plaque, 

 oval in shape with a dense blackish front rim (Fig. MM133Z), E). These are 

 about 15/x across. The number of papillae in the metameric part varies 

 between 50 and 70 pairs. In the male a pair of small rounded genital papillae, 

 which meet in the mid-ventral line, is situated almost on the boundary 

 between the mesosoma and metasoma (Fig. MM1332?). 



The nonmetameric section of the trunk is very long and furnished with 

 small contracted irregularly spaced papillae. No zone of thickened papillae has 

 been observed. There are three girdles — two anterior and one much farther 

 back. Each girdle is represented by a rather narrow annular ridge on which 

 the toothed platelets are arranged in a single row (Fig. NN133$, C). The first 

 girdle is broken dorsally, the second ventrally and third has a broad ventral 

 gap (Fig. NN133^), but in one individual the first girdle is almost complete, 

 while the second makes more than a complete turn around the trunk. There 

 are no papillae within the girdle region, but where the postannular region 

 begins, at the point of constriction of the trunk, there is a small plaqueless 

 papilla (Fig. NN133^). 



The shape of the toothed platelets varies enormously. In one individual 

 they are greatly elongated and most of them have the hind end narrower 

 (instead of the usual condition, which is the reverse). Often there is a trans- 

 verse line cutting the platelet into two almost equal parts, one bearing the 

 anterior and the other the posterior group of teeth (Fig. NN133C, D). 

 The anterior group of teeth is usually the more poorly developed, though 

 the reverse may occur. In the former case the front half of the platelet 

 is not only broader than the hind half but also thicker and sometimes 

 even inflated (Fig. NN1332?). The platelets are 10-17/x long. Sometimes 

 one may encounter anomalous short platelets, bearing only one group 

 of teeth. 



The postannular region of the metasoma is unfortunately only known in 

 part from three individuals. It is furnished with metameric conical ventral 

 papillae, near which the integument of the trunk is rich in large glandular 



