§ 2 HOMOLOGY OF PITUITARY LOBES 6i 



cation of each lobe. In the Teleostei we also find examples 

 in which the lobus tuberalis is connected rather loosely with 

 the lobus anterior, as in Anomalops (Fig. 5 i A, III). Finally, 

 in amphibia the lobus tuberalis is quite separate from the 

 hypophysis, and lies cranially, as a pair of glandular islands, 

 one on each side of the hypophysis (Fig. 51B, X) . In young 

 Xenopus, however, the lobus tuberalis is still connected with 

 the lobus anterior. In other animals the lobus tuberalis and 

 the lobus anterior form a single lobe. Thus we failed to find 

 an independent lobus tuberalis in Hippocampus, Anguilla, 

 and Lophius (Fig. 51 A, V). These two movements of the 

 lobus tuberalis, resulting in independence and movement 

 upwards, already observed in fishes, are carried still further, 

 as we shall see, in amniotes. 



In reptiles and mammals this lobe often consists of loose 

 strands of cells, as in birds, or of a plate whose shape 

 resembles something between a shield and a funnel (Felis, 

 Fig. 51B, XVI), surrounding the tuber cinereum. This 

 position formerly caused it to remain unobserved, and led to 

 the familiar but erroneous three-lobe division of the hypo- 

 physis. 



e. The topographical interrelation between lobus inter- 

 medius and lobus posterior. 



There is a constant topographic relation between the lobus 

 intermedius and the lobus posterior. In fishes, with their 

 relatively large lobus intermedius, the main region for the 

 extension of the lobus posterior is situated in the lobus inter- 

 medius. However much the lobes may have shifted with 

 respect to one another as a result of a shift of the axis, the 

 lobus intermedius will always be found lying around the 

 body of the lobus posterior. In Petromyzon the lobus inter- 

 medius is still quite free from the lobus anterior and lobus 

 tuberalis and lies closely against the flat lobus posterior (Fig. 

 5 I A, I). In Zoarces, with its caudo-basal hypophysial shift, 

 it lies in the centre of the hypophysis (Fig. 51B, IX), both 

 lobes, in this case, being surrounded by the lobus anterior. 

 This is also the case in Phomoxis. In amphibia, where the 



