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Show 1891.] EARTHWORM FROM WEST AFRICA. 51 with Levinsen's figure (loc. cit. pi. vii. figs. 3, 5), the "spear-head " is longer than the shaft. Viewed laterally (fig. 3, a) each seta is seen to be curved from above downwards. Each of these seta? is invariably accompanied by an immature seta, the form of which can be understood by reference to the accompanying sketch (fig 3, c) without any detailed description. Fig. 3. Genital setae of Siphonogaster millsoni. a, seta viewed in profile; b, ventral view of seta ; c, immature seta. Levinsen naturally regards these structures as copulatory organs, but considers that they may also have a respiratory function ; this' latter would seem possible on account of their large size and the rich plexus of blood-vessels with which they are furnished. The small size of the appendages in S. millsoni is against their performing a respiratory function in that species, but I quite a^ree with Levinsen in believing that they are in all probability penes. Their position on the body and the spicules with which they are furnished favour this view. The genital setae of this Siphonogaster bear a very close resemblance to the genital setae of Nais elinguis, which have recently been figured for the first time by Dr. A. Stole1; the spear-head form and the proportions between the head and " shaft" appear to be nearly identical in the two forms ; the curvature, too, exists in both, though it is considerably more pronounced in Nais elinguis than in the worm which forms the subject of the present communication. This case of an Earthworm possessing setae like those of the lower aquatic forms is very rare ; indeed only one other example is known to me-that is, Urochceta, in which Perrier first described the 1 "Pfispvesky ku studiu Naidomorph," SB. bohm. Gesellsch. 1887, p. 227 4 * ' |