. Bulletin of the British Museum (Natural History) Zoology. Fig. 6 Pallial complex; A. Rhachistia chiradzuluensis, Thika, Kenya; B. Rhachistia histrio, Mare, Loyalty Islands. Scale line 2 Fig. 7 Pallial complex, Edouardia cf. metula, Nairobi, Kenya. Scale line 2 mm. the penis above the level of appendicular insertion. This is only attached at one end but may be directed upwards (eg. Rachis, Fig. 23A; Pachnodus, van Mol & Coppois, 1980, Fig. 5) or downwards (eg. Rhachistia, Fig. 18A; Conulinus, Fig. 20C) from the point of attachment. In some cases the downwardly directed muscle is recu
. Bulletin of the British Museum (Natural History) Zoology. Fig. 6 Pallial complex; A. Rhachistia chiradzuluensis, Thika, Kenya; B. Rhachistia histrio, Mare, Loyalty Islands. Scale line 2 Fig. 7 Pallial complex, Edouardia cf. metula, Nairobi, Kenya. Scale line 2 mm. the penis above the level of appendicular insertion. This is only attached at one end but may be directed upwards (eg. Rachis, Fig. 23A; Pachnodus, van Mol & Coppois, 1980, Fig. 5) or downwards (eg. Rhachistia, Fig. 18A; Conulinus, Fig. 20C) from the point of attachment. In some cases the downwardly directed muscle is recurved to form a double- layered structure (eg. Cerastus, Fig. 19B; Achatinelloides, Fig. 24A). The arrangement appears to be constant within species but, on the evidence of Euryptyxis, may vary between congeneric species (Mordan, 1986). The sheath is generally weaker in flagellate genera, and in Edouardia (Fig. 15A) is barely visible, being extremely fine, single-layered, and closely adpressed to the wall of the penis. As the sheath was found in all cerastine taxa, it was not utilised in the analysis. The form of the cerastine epiphallus (character 4), and hence of the spermatophore which it secretes, is broadly correlated with penis type. Flagellate groups such as Edouardia (Figs 10, 11) and Rhachistia (Figs 12, 13), have an externally simple epiphallar region, only distinguishable from the vas deferens by the greater thickness of the former. Internally, the epiphallus is ornamented with longitudinal, sometimes spiral folds which in the case of Rhachistia rhodo- taenia appear to correspond to the pair of fins which extend along about half the length of the spermatophore (Figs 14B, 25). In this species the fin becomes finely serrated along part of its length, as in some Eninae (Schikow, 1978). In contrast, the non-flagellate taxa have a spermatophore characterised by a longitudinal row of strong, discrete, hooked spines which may bear forked or complex digitiform terminations (H
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