The Tanganyika problem; an account of the researches undertaken concerning the existence of marine animals in Central Africa . has been cut open from above,and the radular sac exposed. The intestine passes out of the stomach beneath the tubularaperture between the posterior and anterior stomachicchambers, as indicated in the drawing on page 251. Theintestine is coiled in the manner seen on page 251, andtowards its rectal extremity it contains a number ofglandular folds and striae. The liver is large, and occupies the lower two-thirds of THE TANGANYIKA PROBLEM. 253 the last two whorls of the an
The Tanganyika problem; an account of the researches undertaken concerning the existence of marine animals in Central Africa . has been cut open from above,and the radular sac exposed. The intestine passes out of the stomach beneath the tubularaperture between the posterior and anterior stomachicchambers, as indicated in the drawing on page 251. Theintestine is coiled in the manner seen on page 251, andtowards its rectal extremity it contains a number ofglandular folds and striae. The liver is large, and occupies the lower two-thirds of THE TANGANYIKA PROBLEM. 253 the last two whorls of the animals body. There is a singlebile duct, opening, as has already been stated, in the posteriorchamber of the stomach. The heart has the normal taenioglossate characters, andconsists of a thin-walled auricle, a thick-walled ventricle, anda short aortic trunk. Between the auricle, ventricle, andaortic trunks there are the usual valves. The gill ofNassopsis is of average length, very simple in structure, andconsists of a large number of low, broad, triangular leaves,the apices of which are not produced into filamentous pro-. Fig. 36.—The lingual dentition of Nassopsis nassa. cesses, nor ornamented in any way. The osphradium islong and simple ; it lies in a groove at the base of the gill,and shows no tendency to become pectinated or modified inany way either before or behind. The nervous system of Nassopsis (Fig. $7) ls extremelyinteresting, being one of the most archaic taenioglossate typesat present known. The cerebral ganglia are widely separatedfrom one another, and the pleural ganglia are not onlyseparated from the cerebral ganglia, but on the sides of theoesophagus, the cerebro-pleural connectives being conse-quently of considerable relative length. The supra-intestinalcord springs directly from the right pleural ganglion, passes 254 THE TANGANYIKA PROBLEM. up over the oesophagus, and carries the supra-intestinalganglion. From the left pleural ganglion there passes a finener
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectm, booksubjectzoology
