402 



PART II. SYSTEMATIC ACCOUNT 



which come into close contact with each other, though they are wide apart 

 dorsally (Fig. 16(L4, B). The boundary between the mesosoma and the 

 metasoma is a straight annular groove. The first part of the preannular 

 section of the metasoma has c. 23 pairs of small, regular adhesive papillae and 

 the ventral sulcus between them is well marked (Fig. 16(L4). In the zone of 

 thickened papillae the 15-20 higgledy-piggledy ventral papillae are furnished 

 with plaques c. 4<V across, while the oval plaques on the metameric papillae 

 of the front part of the trunk are с 30^ across. They are the usual delicate 

 membranes with a thick dark crescent along the front edge. In the non- 

 metameric region of the trunk they assume a rounded outline and become 

 somewhat bigger, reaching 40/л in diameter. The region of the girdle and 

 postannular section of the metasoma are unknown. 



The brown-black tube is quite extraordinary, consisting of a series of 



Table 5 

 Characteristics of the species of Polybrachia 



