CHABACTEBS OF RECENT CROCODILIA. 23 



outermost ventral scutes thin oft' and are not united with any 

 bony element ; and the ventral, like the dorsal scutes, are usually 

 arranged sj^mmetrically on either side of the median sutural line. 

 There may be as many as twenty-two scutes united by their lateral 

 sutiu-es into a single strong, curved, transverse, bony, bar-like 

 segment of the ventral armour. 



Throughout the neck and body, and as far as the commencement 

 of the tail, the ends of the dorsal and ventral bony bars, whose 

 sum may be regarded as a dorsal and a ventral shield respectively, 

 are separated by an interval of integument, in which only small 

 scattered scutes are visible. The ' physiological import of this 

 arrangement becomes obvious when we consider in what manner 

 the animal breathes ; and indeed the integumentary interval 

 answers very precisely to the leather which connects the two 

 boards of a beUows. Again, though the limbs are themselves 

 covered with articulated scutes, they are afforded free play upon 

 the body by this flexible interspace. Immediately behind the 

 hind legs, the ventral and dorsal shields unite ; and the tail is from 

 that point surrounded by a succession of bony hoops, each of 

 which corresponds with a vertebra, the segments of the exoskeleton 

 answering to those of the endoskeleton. 



The most remarkable feature about the ventral scutes, however, 

 and that in which they differ most widely from the dorsal ones, con- 

 sists in the fact that each scute is composed of two distinct pieces, 

 an anterior and a posterior, which unite together by a transverse 

 serrated suture. The anterior piece or ' semi-scute ' may attain 

 to three-quarters the length of the posterior, and it has exactly the 

 same width. The anterior semi-scute bears the articular facet and 

 the transverse pitted groove, whose posterior wall is just in front 

 of its hinder edge, or in other words, of the suture, when the two 

 semi-scutes are united. 



Such are the general characters and mode of arrangement of the 

 dorsal and ventral armour of Jacare. Bu.t there remain many 

 noteworthy peculiarities in the disposition and number of the 

 components of each band of the armour. 



Thus, in the dorsal shield there are two rows of nuchal scutes, 

 each containing eight separate keeled bony plates ; and of cervical 

 scutes there are five rows, the two anterior of which contain four 

 angulated and cariuated scutes each, while the three posterior con- 

 tain only two scutes each. All these scutes, except the anterior 

 row, have articular facets ; and all those of each row are united 

 suturally. Of dorsal scutes there are thirty transverse rows up to 



