The Tanganyika Problem Reviewed 465 



level, but at elevations of from 2000 feet, to fully 4000 

 feet. Thus the examples from Tanganyika occur at about 

 2700 feet, those from Victoria, from the Zambesi, and 

 from the Norquane of the Limpopo system are from 4000 

 to 4500 feet elevation; that from the Krishna in West 

 India is at 2100 to 2200 feet. This becomes an important 

 consideration in any attempted explanation of faunal 

 origins, and will be discussed later. Another feature that 

 merits passing attention is that equally in the African and 

 Indian medusae these are infested by an infusor — Tricho- 

 dina pediciiliis — that is "able to lead an endoparasitic ex- 

 istence within the gastrovascular system of the medusae."- 

 The genus Trichodina has only been "found on the surface 

 of Hydra, Sponges, Planarians, and other freshwater ani- 

 mals, and also occasionally in the bladder of Frogs, Newts, 

 and Fishes." These medusae then must be added to the 

 list of hosts. 



Of Polyzoa six freshwater species are now known from 

 Lake Tanganyika, three of which belong to the sub-class 

 Phylactolaemata, and three to the Gymnolaemata. All 

 of them, in their semicolonial mode of growth, and strongly 

 individualized polypides, suggest primitive forms of the 

 Class (7:391). Most of the Tanganyika genera also are 

 of wide geographic distribution, and all are wholly of fresh- 

 water habitat. Thus Phimatella is found in nearly every 

 region of the world, while Fredericella, Pectinatella and 

 VictoreUa are becoming known from more and more wide- 

 ly removed localities. The existence then of these and of 

 some other species in the central African lakes, would be 

 added proof that solitary or semicolonial freshwater poly- 

 zoa are and have been much more important and wide- 

 spread types of faunal life than has usually been accepted, 

 while it helps to confirm the above-cited conclusions already 

 published by the author. 



Of higher Crustacea three were described from Moore's 

 expeditions. One of these, Palaemon moorei, belongs to 

 a family — Palaemonidae — that is now largely marine, but 

 some freshwater and brakish species have a wide distribu- 

 tion. The latter, we hope to show in another work, are 

 persistent survivals of primitive members of the family 



