44(i 



ANATOMY OF VERTEBRATES. 



projecting into the caecum, which is continued beyond, spirally, 



and contracting to open into the colon by a rounded puckered 

 aperture, at the end of a conical valvular prominence. Valvular 

 folds of the mucous membrane project into the colon from its 

 concave side, decreasing in breadth as they descend. The coats 

 of the intestine make smaller indentations from the convex side, 

 opposite the intervals of the larger folds. Beyond these folds the 

 colon diminishes in diameter, and makes a sudden turn upon 

 itself before becoming the ' rectum.' The crecum is, here, not a 

 mere ' caput coli,' but a distinct segment of the alimentary canal, 

 having an orifice for ingress, and a second for egress, of contents, 

 analogous to the cardia and pylorus of the stomach, with parietes 

 more muscular than either of the intestines with which it com- 

 municates. 1 



It would seem, from petrified contents or excretions of the 

 intestine, that some part, probably the terminal one, of this canal 

 had been provided, in the extinct Ichthyosaur, with a spiral valve, 

 fig. 105 ('coprolite' figured below the pelvis). 



The rectum does not open directly upon the exterior of the 

 body in any Reptile, but into a cavity, or ' cloaca,' common to it 



1 The following Table (ccxlv. p. 92) gives the weight of the body, in grains, and 

 the lengths of the alimentary canal, in inches, in various Reptiles. 



Menopomu alleghaniensis 

 Sana Catesbiana (Bullfrog) 

 Heterodon niger (Black viper) 

 Psammophis'flageiliformis (Coachwhip snake) 

 Coluber guttatus (Corn snake) 

 Coluber constrictor (Black snake) . 

 Crotalus adamanteus (Rattlesnake) 

 Alligator mi&sissippiensis (Alligator) 

 Chelone caretta (Loggerhead turtle) 

 Chelydra serpentina (Snapping turtle) . 

 Emys reticulata (Chicken terrapin) 

 Emys serruta (Yellow-bellied terrapin) . 

 Testudo Polyphemus (Gopher) 

 Trionyx ferox (Soft turtle) . 



Menopoma alleghaniensis 

 Rana Catesbiana . 

 Chelydra serpentina 

 Testudo Polyphemus. 



Length 

 of body 



inches 



32 

 68 

 54 

 54 

 48 



"Weight of Length of 

 the body the canal 



grains 



9,800 

 4,620 

 5,141 

 9, 600 



5, 100 



6, 180 

 211,940 

 36,985 

 16,235 



8,400 

 27, 172 

 45, 500 



inches 

 24 

 34 

 26 

 42 

 54 

 36 

 42 

 147 

 102 

 46 

 38 

 66 

 78 

 48 



Length 

 of large 



intes- 

 tines 



inches 

 6 



10 

 46 



