92 THE POPULAR SCIENCE MONTHLY, 



is but very feebly represented in man. " Padding " accounts for 

 all the rest a little more or less of fat and cellular tissue. 



"Every face however full, 

 Padded round with flesh and fat, 

 Is but modeled on a skull," 



and it tells the same tale of the rest of the figure. It seems an 

 odd statement at first sight, but there are many millions of beings 

 who have an outside instead of an inside skeleton. What a miser- 

 able existence these poor creatures must have if they have a good 

 figure, for it can not be exhibited ! The lobster is of the 40-exo- 

 skeleton type. 



I have dealt with necks, now for the other extreme. It might 

 be argued that one great difference between ourselves and the rest 

 of the vertebrates is marked by the fact of our having no tail. 

 We all have tails. 'Tis true they are wretched specimens, but 

 they exist universally. We do not wag our tails, but only the 

 other day I spoke with a gentleman who had a dog whose caudal 

 vertebrae were anchylosed together. A little careful selection with 

 this dog, and it is probable that a race of dogs might be developed 

 with an os coccygis like ourselves. Disuse invariably leads to 

 abortion. The little mass of anchylosed vertebrae that we call the 

 OS coccyx is our best apology for a tail, but this region of the spinal 

 column becomes wonderfully modified and developed if we com- 

 pare it with its homologue in other members of the creation. It 

 may act as a hand, may be the exclusive locomotive organ, it may 

 contain the only free vertebrae in the body. In the spider monkey 

 it is prehensile and is often used as a hand. In some sharks the 

 number of the vertebrae amounts to two hundred and seventy. In 

 tortoises the coccygeal vertebrae are the only free vertebrae. In 

 the sole the neural spines and the hypophyses are remarkably de- 

 veloped. Finally, the bone may be even more rudimentary than 

 in man. In the bat there are but two coccygeal vertebrae. 



Quite a developed tail has, says Marshall, been discovered in 

 the human race in certain rare and anomalous cases. 



In the embryonic stage of the vertebrates the spinal column is 

 represented by the so-called notochord, and this notochord is tem- 

 porarily represented in the Ascidians, a class of animals bearing 

 not the remotest resemblance to the Vertebrates. This is a highly 

 interesting fact in connection with the interrelation of species. 



One other most interesting fact : At an early period of our de- 

 velopment that is to say, at an early part of our embryo existence 

 the OS coccyx is free and projects beyond the lower extremities. 



One other less interesting fact : What tail we have is always 

 carried between our legs no doubt, in the majority of instances, 

 there is good reason for it ! 



