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P.R. PUGH 



The basic Bargmannia ridge pattern is supplemented by a pair of 

 short ridges (Figures 2A, sb; 3 A) that branch from the apico-laterals 

 (Figure 2A, ml) at the point where the latter bend sharply, through 

 90°, away from the mid-line. This sharp bend typically can be seen 

 in less well preserved specimens and is characteristic for this 

 species. The side branches are directed, for a short distance, toward 

 the deep median furrow. In many specimens, particularly net col- 

 lected material, they were difficult to discern but often can be seen 

 after staining. Basally, the inner branch of each apico-lateral ridge 

 curves inwards and then down to reach the ostium (Figure 2 A, bi), 

 except for immature nectophores (Figure 3A) where it ends slightly 

 above that level. Each outer branch (Figures 2A, bo; 3C) typically 

 terminates on or just above one of the small, but prominent, lateral 

 processes on either side of the ostium. 



Basal extensions of the meso-lateral ridges form the baso-lateral 

 margins of the bilobed mouth-plate (Figure 2B, mp; 2C), each lobe 

 being thickened ventrally, particularly toward the mid-line. Basally, 

 the two lobes typically overlap and unite, in the mid-line, at about 

 half the height of the mouth-plate (Figure 3C).The lower nerve tract 

 (see Mackie, 1964), which can be traced down the nectophore, 

 beneath its ventral surface in the mid-line, recurves at this point and 



continues obliquely to the baso- ventral margin of the ostium (Figure 

 3C). In immature nectophores the mouth-plate is not thickened and 

 has a U-shaped emargination in the mid-line (Figure 3A, B) which is 

 deepest in the youngest nectophores. 



Above the mouth-plate, the basal extensions of the meso-lateral 

 ridges curve round toward the mid-line, on the ventral surface of the 

 nectophore (Figure 2 B), before looping back outwards as the meso- 

 laterals proper (Figure 2C, mil). The infra-laterals are weakly 

 defined in the region where they divide from the meso-laterals, and 

 in younger nectophores clearly terminate before reaching the latter 

 (Figure 3 B). The meso-laterals curve up, obliquely, across the 

 lateral surface to reach the junction with the other main ridges at a 

 level slightly below the apex of the nectosac (Figure 2C). The 

 connection with the other ridges is weak, and often the meso-laterals 

 appear to end slightly below the junction, as was found for younger 

 nectophores (Figure 3 A). 



The infra-laterals (Figure 2B, ril) demarcate the ventral margins 

 of the thickened walls of the more basal part of the ventro-lateral 

 wings. In lateral view these wings are slightly emarginate in outline. 

 Apical to where the infra-laterals curve up to join the other ridges, 

 the wings remain well developed and are thickened with mesogloea. 



Fig. 3. Bargmannia elongata. A. Upper and B. lower views of young nectophore; C. detail of ostial region of mature nectophore. Scale bar = 1 mm. 



