The Tanganyika problem; an account of the researches undertaken concerning the existence of marine animals in Central Africa . e courseof two well-developed scalariform pedal cords. Betweenthese pedal cords there exist ladder-like connectionssimilar to those found between the pedal cords ofCyclophorus. The otocysts in Nassopsis are relatively immense. Theyare situated well up on the course of the pedo-pleural con-nectives, and the otocyst nerves pass obliquely from themtowards the cerebral ganglia. The otoliths are small,numerous, and rectangular, with the faces slightly convex. The reproducti
The Tanganyika problem; an account of the researches undertaken concerning the existence of marine animals in Central Africa . e courseof two well-developed scalariform pedal cords. Betweenthese pedal cords there exist ladder-like connectionssimilar to those found between the pedal cords ofCyclophorus. The otocysts in Nassopsis are relatively immense. Theyare situated well up on the course of the pedo-pleural con-nectives, and the otocyst nerves pass obliquely from themtowards the cerebral ganglia. The otoliths are small,numerous, and rectangular, with the faces slightly convex. The reproductive apparatus in iVassopsis is somewhat 256 THE TANGANYIKA PROBLEM. similar to that of Typhobia, both male and female apparatusoccupying the same position as the body wall. In the malethe genital gland occupies the upper surface of the apicalwhorl in the body, and is connected by several channelswith a nearly straight vas deferens. This latter structureopens without any modifications along its course by a slit-like aperture. In the female the ovary occupies the sameposition as the male gland, and in like manner it is con-. Fig- 39-—Shell of Spekia zonata. nected with the nearly straight oviduct, the lower portionof which, or that which lies within the mantle cavity,forming a brood chamber where the eggs go throughtheir later stages of development, the animal being vivi-parous. SPEKIA, CROSS. S. ZONATA. (FIG. 39). The shell of this remarkable mollusc is representedin Fig. 39, and it is certainly most curious that noattention has been drawn by any of the conchologists to THE TANGANYIKA PROBLEM. 257 the extremely naticoid character which it presents, for theshell of this species is so completely similar to that ofnumerous fossil naticoid forms that, had it appeared fos-silised instead of having been found living in a great fresh-water lake, there is not the slightest doubt that it wouldhave been placed in one of the numerous fossil generawhich are supposed to group themselves abo
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