The Tanganyika problem; an account of the researches undertaken concerning the existence of marine animals in Central Africa . we must conclude that Tan-ganyicia possesses an archaic character which may beencountered in part, or in entirety, in widely diversemolluscan types. See fig. on p. 273. Tanganyicia may thusbe said to exhibit the morphological characteristics whichwe should attribute to those earlier members of the Proso-branchiate group which anteceded the modern forms typifiedby such genera as the Strombus and Cerithium of to-day. In Spekia we have a form which, in its nerves, isunque
The Tanganyika problem; an account of the researches undertaken concerning the existence of marine animals in Central Africa . we must conclude that Tan-ganyicia possesses an archaic character which may beencountered in part, or in entirety, in widely diversemolluscan types. See fig. on p. 273. Tanganyicia may thusbe said to exhibit the morphological characteristics whichwe should attribute to those earlier members of the Proso-branchiate group which anteceded the modern forms typifiedby such genera as the Strombus and Cerithium of to-day. In Spekia we have a form which, in its nerves, isunquestionably a naticoid, but which, in the absence of anumber of the more specialised naticoid structures, suchas the glandular masses related to the oesophagus, and soon, is unquestionably simple ; and the same conclusion isforced upon us, both by the early Cerithoid character of itsradula and possession of the archaic gastric apparatusand crystalline style, characteristic of all the halolimnicforms. Spekia would in many ways appear to be very likea primitive Rissoa. Turning now to the last, and perhaps the most interest-. g. V.
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