22 



Einar Lönnberg, 



In general outline the liver of C. melanorhoeus is less transver- 

 sally elongate than that of C. maxwelli as figured by Garrod (1. c). 

 Its longest diameter from left to right is 91 mm. the greatest width 

 (right lobe) is about 04 mm. and the greatest thickness (left lobe) is 

 30 mm. It is thus a rather compact organ. Fissura umbilicalis extends 

 about 2 cm. from the margin and not quite that on the diaphragmatic 

 side, and there are no other fissures. The Spigelian lobe is large, 

 triangular, with the rounded apex extending fully three cm. from the 

 posterior margin. The caudate lobe is also large, bayonet-shaped and 

 only coming 1 cm. short of the anterior free margin of the right lobe. 

 The right kidney is capped by the extreme right portion of the liver 

 and the caudate lobe. 



The question why the gallbladder is missing in some animals 

 is most puzzling and the reason why it is missing in some but not in 

 others is certainly not easily explained. Owen put it together with the 

 shape of the stomach, but got no definite rule. It seems to me more 

 suitable to put the presence resp. absence in connection with some 

 certain kind of diet. The presence of a gall-bladder is the primary 

 condition, that can be concluded from the fact that such an organ is 

 found as well in the lower vertebrates as in the most primitive mam- 

 mals for instance Monotremata and Marsupialia. With the exception 

 of the whales all other mammals 1 ) in which the gall-bladder is missing- 

 feed on vegetable matter of some kind. If the gall-bladder is present 

 in one, but absent in another of two related genera the latter is, as a 

 rule more confined to a vegetable diet. An illustration of this is pre- 

 sented by the genera Sus with and Dicotyles without gall-bladder but 

 with a complex stomach indicating a vegetable diet. This seems to 

 indicate that the gallbladder is of less importance for herbivorous ani- 

 mals so that it may sometimes as in Qiraffa or always as in CartiektSj 

 Cervidœ etc. be absent. It is true that the gall-bladder is present also 

 in many herbivorous animals, as for instance in most Cavicomia, but 

 that does not disprove the hypothesis that it could be reduced without 

 inconvenience, while it seems certain that it would be more incon- 



') According to the literature the gall-bladder seems to be absent in the following 

 mammals (in addition to the whales) Bradypus tridactylus, Tapirus, Rhinoceros sondiacus, 

 Equus, Dicotyles, Camelus, Giraff a (sometimes), Cervidœ, Elephas, Lamnunguia, Mus, Cri- 

 cetus, Lenimus Echimus, Erethizon, Synetheres, Tamias all of which feed on vegetable sub- 

 stances, or if exceptions to that rule may take place, as with some members of the genus 

 Mus, this is secondary. 



