. Bulletin of the Natural History Museum Zoology. 60 PUGH mm; mean width ± mm; and the ratio of the overall length to that of the nectosac averaged ± Finally six specimens had even larger nectophores and were sexually mature. They averaged nectophores, whose mean length was ± mm; mean width ± mm; and the ratio of the overall length to that of the nectosac averaged ± As was the case forB. elongata, the apex of the thrust block of the smaller specimens was drawn out to form a small digitiform process (Figure 8A). In the larger s
. Bulletin of the Natural History Museum Zoology. 60 PUGH mm; mean width ± mm; and the ratio of the overall length to that of the nectosac averaged ± Finally six specimens had even larger nectophores and were sexually mature. They averaged nectophores, whose mean length was ± mm; mean width ± mm; and the ratio of the overall length to that of the nectosac averaged ± As was the case forB. elongata, the apex of the thrust block of the smaller specimens was drawn out to form a small digitiform process (Figure 8A). In the larger specimens, this process usually became folded over onto the ventral side of the nectophore (Figure 7C), so that, in upper view, the thrust block appeared roundly truncate (Figure 7A). The apico-lateral ridges are, in their preserved state, smoothly curved and have no pronounced bend or side branches (Figures 7 & 8), as was found for B. elongata. After these ridges divide, the inner branches extend obliquely down to reach the ostium; while the outer branches curve down the sides of the nectophore, but peter out well above ostial level. The latter is particularly marked on the smaller nectophores (Figure 8C). Basal extensions of the meso-lateral ridges form the baso-lateral margins of the mouth-plate (Figures 7 & 8). The structure of the mouth-plate varies with the size of the mature nectophore. In the smallest specimens, the mouth-plate is only slightly truncate basally (Figure 8A). In the middle size range of specimens, the mouth-plate becomes more and more emarginate and, in the largest ones, it has a narrow U-shaped median indentation stretching up to the ostium (Figure 7A). The mouth-plates of the immature nectophores of all sizes of specimens show the same features as the corresponding mature ones (Figure 9). Above the mouth-plate, in the small and medium sized speci- mens, the basal extensions of the meso-lateral ridges curve slightly in toward the mid-line (Fi
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