. Bulletin of the British Museum (Natural History) Zoology. Fig. 67 Ledella ultima: Vertical transverse section through stomach and hind gut coil as viewed from anterior side ( morphological right is topographically left). (Scale = mm).. The pedal ganglia are large (Fig. 67). The cerebral and visceral ganglia are smaller and club-shaped, the visceral ganglia lying anterior to the posterior adductor muscle. The smallest individual recorded with discernible gonads was mm in length. Development was assessed in two samples, one from the western Atlantic (Sta. 101) and the other from th
. Bulletin of the British Museum (Natural History) Zoology. Fig. 67 Ledella ultima: Vertical transverse section through stomach and hind gut coil as viewed from anterior side ( morphological right is topographically left). (Scale = mm).. The pedal ganglia are large (Fig. 67). The cerebral and visceral ganglia are smaller and club-shaped, the visceral ganglia lying anterior to the posterior adductor muscle. The smallest individual recorded with discernible gonads was mm in length. Development was assessed in two samples, one from the western Atlantic (Sta. 101) and the other from the eastern Atlantic (BGIV DS53). The maximum diameter of the ova in different mature individuals varied from 160-280 urn (Sta. 101) and from 220-255 urn (BGIV DS53). Ova were few in number, 6-29 per individual at both Stations most being in the left side of the body, diametrically opposite to the coils of the hind gut. Individuals from Station 101 with thickened shell margins (> mm) were compared with ones without a thickened margin ( mm in length, however, not all individuals above this length exhibit thickening (Fig. 70). The maximum recorded thickening was mm in an individual shell mm in length. The feature is formed following a sharp change in the spiral angle of growth of the shell to produce a flattened edge. While not a unique occurrence among deep sea protobranchs it is by far seen at its most extreme in Ledella ultima. It is possible that it may be a feature of those specimens that are maturing for a second or more time. Because of the multiplicity of names given to this species, various shell parameters from samples from different basins of the Atlantic were measured and compared (Figs. 69, 71, 72 & 73). The Stations selected were:- Walda DS31 (Guinea. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resem
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