LAMELLISABELLA MINUTA 439 



The boundary between the mesosoma and metasoma is a somewhat 

 bevelled groove, which takes a dip forward in the mid-dorsal region. The 

 dorsal ciliated band starts in this dip and extends backwards to the end of 

 the metameric part of the metasoma. There is a comparatively narrow but 

 deep ventral sulcus running between lateral ridges (Fig. В 169^4) which bear 

 the metameric pulvilli of the adhesive plaques. The adhesive papillae them- 

 selves hardly project from these ridges. As in other species of Lamell- 

 isabella, their metamerism is very imperfect. Thus in one specimen the 

 papillae are arranged in more or less regular metamerism in the anterior 

 part of the metameric region, but farther back this regularity breaks down 

 so that the sixteenth plaque on the right is opposite the seventeenth on the 

 left and the twenty-third on the right opposite the twenty-fifth on the left 

 (Fig. A169). The metameric part of the second individual is much the same, 

 as is one of the fragments which includes this part. 



The strongly contracted pulvilli of the plaques in the anterior part of the 

 metameric region are equilateral triangles with chamfered corners (Fig. 

 C1695), but in the hind part of the region they become round (Fig. C169C). 

 The plaques, as in all known species of Lamellisabella, appear horseshoe- 

 shaped. Attentive examination, however, shows that they are in fact round, 

 but enormously thickened at the front as a sort of dark-brown horseshoe- 

 shaped catch, whose short ends stick out backwards like a ratchet (Fig. 

 C169.5, C). The ends of the horseshoe reach to the middle of the plaque and 

 the remaining part is a sort of thin flat transparent roundish scale (Fig. 

 CI 695, C). Thus the structure of the horseshoe plaques is the same as in 

 other species of Lamellisabella (I vanov, 1957; Kirkegaard, 1961; see p. 47). 

 The horseshoes in L. minuta are 34//. across and the plaques themselves vary 

 from 44 to 52/*. 



The horseshoe plaques are limited to the metameric part of the pre- 

 annular region, but, as in L. zachsi and L. johanssoni, here and there simpler 

 'bow-shaped' plaques without apodemes replace the horseshoes. In one 

 specimen, which has 23 plaques on the right and 25 on the left in the meta- 

 meric region, the nineteenth pair of pulvilli are the last to bear horseshoes, 

 but the fifteenth and seventeenth pulvilli on the left bear 'bows'. In the other 

 individual, which has 25 pulvilli on each side of the body, the seventeenth 

 pair bear the hindmost horseshoes, but the seventh and tenth pulvilli on 

 the left and the fifteenth on the right have 'bows'. The oval plaques with the 

 'bows' have their major axis athwart the body and the dark bow-shaped 

 thickened rod reaches 40/li across (Fig. C169Z)). 



The nonmetameric section of the prcannular region of the metasoma is 



