444 CROCODILIA CHAP. 



from the glottis backwards. The lungs have attained a high 

 degree of efficiency. Each lung is an oval sac, and is transformed 

 into a complicated system of tubes, at the end of which are the 

 countless honeycomb-like respiratory cells, the whole lung being 

 spongy. The main bronchus is continued straight down to the 

 posterior end of the lung, and sends off during its coiurse regular 

 secondary bronchi, and these send off tertiary bronchi. The 

 whole arrangement is very regular, the tubes coming off like rows 

 of organ-pipes. Each lung hangs freely in the thoracic cavity. 

 Besides its ventral attachment by its arteries, veins, and the 

 bronchus, it is connected T»y loose tissue with the liver and the 

 pericardial septum. Each half of the thoracic cavity is partitioned 

 off from the abdominal cavity by a strong transverse mesenteric 

 lamella. The partition between the lungs and the stomach is at 

 first simple, it then divides, to enclose the liver ; the anterior 

 partition passing between liver and lung to the inner surface of 

 the sternum ; the posterior lamella between the liver and the 

 stomach. Both meet on the ventral surface of the liver, and are 

 continued into or attached to the peculiar " diaphragmatic " 

 muscle. This is covered by the internal rectus muscle of the 

 abdomen, arising from the last pair of abdominal ribs near the 

 pubic bones ; it is innervated by a branch of the last precrural 

 nerve, and extends as a broad but thin muscular sheath (always 

 within and unconnected with the abdominal wall) to the ventral 

 posterior vein of the liver ; thence it is continvied as an 

 aponeurosis, together with tlie peritoneal lamella mentioned 

 above, to tlie inner surface of the sternum. Contraction of this 

 singular muscle indirectly widens the pulmonary cavity, and 

 thereby directly aids inspiration. It acts consequently like the 

 diaphragm or midriff of Mammals, although it is morphologically 

 an entirely different muscle. 



The stomach is smaller than one might expect from the fact 

 that large Crocodiles can eat up nearly a whole man ; but a great 

 deal of their prey is stowed away preliminarily in the wide gullet 

 until the rapid, powerful digestion, which dissolves every bone, 

 makes room in the stomach. This consists of a wide, some- 

 what glol>ular gizzard, ratlier muscular, with a pair of tendinous 

 centres like those of birds, and a much smaller pyloric, globular, 

 more glandular compartment. It leads into the duodenum, 

 which is coiled up into a double loop, and receives at its end the 



