The Tanganyika problem; an account of the researches undertaken concerning the existence of marine animals in Central Africa . Fig. 27.—Shell of Paramelania damoni (-f ^). the intestine, in the possession of an anterior stomachicchamber and a crystalline style, Paramelania is in allrespects similar to Typhobia, but like Limnotrochus andChytra it does not appear to be viviparous. P. CRASSIGRANULATA, SMITH. This form is in all respects closely similar in thestructure of its soft parts, shell, operculum and radula, toP. damoni. (See Figs. 25 and 26.) 246 THE TANGANYIKA PROBLEM. TANGANYICIA, CROSS
The Tanganyika problem; an account of the researches undertaken concerning the existence of marine animals in Central Africa . Fig. 27.—Shell of Paramelania damoni (-f ^). the intestine, in the possession of an anterior stomachicchamber and a crystalline style, Paramelania is in allrespects similar to Typhobia, but like Limnotrochus andChytra it does not appear to be viviparous. P. CRASSIGRANULATA, SMITH. This form is in all respects closely similar in thestructure of its soft parts, shell, operculum and radula, toP. damoni. (See Figs. 25 and 26.) 246 THE TANGANYIKA PROBLEM. TANGANYICIA, CROSS. T. RUFOFILOSA (FIG. 28). Upon the shore rocks and flourishing among the surfand the breakers of Lake Tanganyika there are severalspecies of small molluscs, which in the fauna of thelake fill the place of the Littorinas and Neritinas ofthe sea shores, and among these littoral forms thereoccurs in great abundance the animal, to the empty shellof which Cross gave the name of Tanganyicia. In itsshell (Fig. 28) Tanganyicia somewhat resembles a smallNatica, but it lacks the callous characteristic of most, if. Fig. 28.—The shell and operculum of Tanganyiciarufofilosa. not all, the shells of the true Naticas. In the generalarrangement of the parts within the mantle cavity, thecharacter of the snout, head, and tentacles, in the positionof the renal, reproductive, and alimentary apertures, and inthe character of its gill, this animal (Fig. 29) very muchresembles Typhobia ; the osphradium is, however, somewhatfoliated at its outer end, and in the female the rectum isprovided with a large rectal gland. In both sexes thegenital aperture is placed farther back than in any of thepreceding forms, and in the male we encounter, for the firsttime among the halolimnic gastropods, an unmistakable THE TANGANYIKA PROBLEM. 247 spermatic groove (Fig. 29) running from the opening ofthe genital duct along the body and on to the foot below
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