LUNGS OF EEPTILES. 525 



of Bipes lepidopus. In Pseudopus Pallasii the lungs are of nearly 

 equal length. 



In most Lacertian Reptiles the lungs are equal, are broader 

 in proportion to their length, and the short bronchus terminates 

 abruptly in the single pulmonary cavity. The parietes are honey- 

 combed and vascular, but in a less degree as they extend from the 

 heart : in Geckos and Agamas the alveoli are deepest on the 

 mesial side of the lungs. In the Iguana the pulmonary cavity is 

 divided by a few deep partitions into primary lodges, the parietes 

 of which are honeycombed by secondary and tertiary cells. 1 In 

 a Monitor (JRegenia ocellata) the bronchus is continued some way 

 alone- the interior of the lung;. 2 The lungs of the Chameleon are 



o o o 



remarkable for their great extent, for the delicacy of their 

 parietes, and the number of ca^cal processes continued from their 

 anterior and inferior margins. Each lung is partially divided 

 longitudinally at its fore part into two cavities, which have their 

 vascular surface increased by subdivision into cellular alveoli ; 

 the posterior appendiculated part of the lung is of a simpler 

 and less vascular structure, and may serve as a reservoir of 

 air. Marginal caecal productions of the pulmonary bag exist also 

 in the Geckos (e. g. Ptyodactylus jimbriatus) and in Polychrus 

 marmoratus. In Geckos and Scinks the trachea terminates in 

 the lungs without dividing into bronchi. 



In the Chelonia the lungs present a further stage of complica- 

 tion, and are adherent to the surrounding parts. In those of 

 Chelydra serpentina, e.g. the general cavity of each lung is divided 

 into eight compartments, the walls of which are honeycombed 

 and vascular, especially at their fore part. The bronchial tube 

 extends to the hindmost compartment of the lung, 3 communi- 

 cating by special orifices with the anterior ones, and sending 

 continuations of its fibrous structure along the free border of 

 the septa. 



In the Sea-Turtles ( Chelone) the lungs extend over the back 

 part of the abdomen to the pelvis, and must act as an air-bladder 

 durino; their swimming : 4 the bronchial tubes are continued. 



O O ' 



gradually decreasing, to near the end of the lungs, and retaining 

 cartilaginous rings or half-rings along three-fourths of their 

 course. They communicate with numerous primary divisions of 

 the pulmonary cavity, each of which is divided into cells, which 

 are subdivided to the third or fourth degree, with proportionate 

 extension of the vascular respiratory surface. The ultimate cells 



1 xx. ib. p. 96. 2 cccxxi. p. 525. 



3 Ib. p. 96, prep. no. 1109 A. * Ibid. p. 96, prep. no. 1110. 



