RUDIMENTARY STRUCTURES. 



245 



This appendage of the coecum, as the " coecum-coli " 

 is called in comparative anatomy, is, however, the 

 rudiment of an organ attaining an enormous size in 

 some of the lower mammals, such as the horse arid 

 rhinoceros, in which it serves as a kind of supple- 

 mental stomach to aid in the absorption of the large 

 quantity of food consumed by these animals. 



Equally noteworthy is the little point of cartilage 

 found in the outer rim of the 

 ear of many persons, and shown 

 at a, in Fig. 82. This little 

 point, the existence of which was 

 first brought to notice by Darwin, ( 

 seems undoubtedly to be the last 

 remnant of the extreme tip of 

 the pointed ears of the lower 

 animals. Its existence appears 

 to be very inconstant, even in 

 members of the same family, FIG 82 _ The human ear 

 for in one family known to the 



writer it is present in the father, but absent in three 

 out of four of his children. 



Perhaps, however, the most interesting instance of 

 a rudimental organ in the whole animal kingdom is 

 the central eye, of which mention has been made in 

 the chapter on " Primeval Salamanders," found buried 

 deep in the brain of the lizard-like Tuatara of New 

 Zealand. Here we actually have a perfect eye, fitted 

 with cornea, lens, and pigment all complete, but totally 

 concealed from all access of light. That this central eye 



