Sip 



snr; 



VERTEHItATE AMMALS. 



In the absenca of inci.sor teeth in the upper jaw, the lower incisors 

 bite against a callous pad of hardened gum. The Camel tribe differs 

 in its dentition from the above t_vpical formula, and certain excep- 

 tions likewise occur in the males of some other forms, and in one or 

 two other less important instances. 



The stomach in the Ruminants is comple.x;, and is divided into 

 sevei-al compartments, this being iu accordance with their mode of 

 eating. Thej^ all, namely, "ruminate" or "chew the cud"; that ij 

 to say, they first swallow their food unmasticated, and then bring it 

 up again after a longer or shorter period in order to chew it. This 

 is effected as follows (fig. 242): The gullet opens at a point between 

 the first two compartments or stomachs, of which the large.st lies to 

 the left and is called the " jiaunch," whilst the smaller right cavity is 

 called the "honeyco.mb bag" (reticulum). The paunch (rumen) is 



Fig. '242.— StoTTianh of a Shce]i 

 ■n:tlcuttim ; p Many-plies 



n riullct ; r Rinain or iiaunch ; /; Huneyconib bag or 

 or jitii'UijriKui ; a Ahjiiu'St'iii or fourth stomach. 



the cavity into which the food is first received, and here it i.i mois- 

 tened and allowed tf> Hir.ik for some time. After the foo<l has lain suf- 

 ficiently long in the juiunch, it passes into the "honeycomb bag," 

 from wliich it is idtimately returned in successive portions to the 

 mouth by a reversed action of the muscles of the gullet. After 

 having been thoroughly chewed, and jjrepared for digestion, the food 

 is now swallowed a second time. On this occasion, however, instead 

 of pa.ssing into the paunch, the masticated food is conveyed into the 

 third stomach. This is known as the " many-plies " or "pxrdterium" 

 because its lining membr.ane is thrown into a number of longitudi- 

 nal folds, like the leaves of a book. Tlie p.salteriuni opens by a wide 

 .ajjerture into the fourth and last stomach, known as the '\ihi)maxiini." 

 Tlii ^ is a cavity of cfjusiderable size, which secretes the true digestive 

 fluid (gastric juice), and it is here that the food is really digested. 



