280 Dynamic Theory. 



Monthly for Oct. 1884, contains a large list of abnormal forms which 

 are found in human subjects. From this article, by permission of the 

 Editor of the magazine, I gather some interesting facts. Some of the 

 abnormalities mentioned will be readily referred to arrested develop- 

 ment, in which conditions that are usually temporary in the embryo, 

 have persisted into adult life ; others belong to the class which we may 

 call divergent crystallizations, or differentiations. Out of nearly 300 

 subjects dissected by Dr. Shepherd, he scarcely found one in which there 

 were no variations from the normal anatomical structure, while many 

 are very abnormal, having as high as thirty or forty variations in their 

 bones, muscles or arteries. They occur oftener in Negroes and Indians 

 than in Europeans. These variations are almost always directly com- 

 parable with structures permanent in the lower mammals. This is so 

 generally the case as to lead to the confident inference that the most of 

 those not thus accounted for will be as soon as comparative anatomy is 

 better known. 



An Epipliyal bone. This bone extends from the temporal bone of 

 the skull, in many of the lower animals, down along the side of the 

 neck, and connects or articulates with the hyoid or little tongue bone. 

 In man this Epiphyal lone does not articulate with the hyoid but is 

 shortened up to a projecting stick-like bone, half an inch long, called the 

 styloid process of the temporal bone, and from the end of it to the 

 hyoid bone there extends a fibrous cord or ligament. Dr. Shepherd has 

 a human skull of low type in which the styloid process is a true epi- 

 phyal bone, 3 inches long and which, in life, did articulate with the 

 hyoid as in the lower animals. This same skull has, on the left side 

 behind the mastoid process of the temporal bone, a stout, bony spur 

 more than |- of an inch long, which has a downward direction and artic- 

 ulates with the first bone of the vertebral column. This is very rare in 

 the human being, but is regular and normal in most graminivorous and 

 carnivorous animals, being especially well marked in the horse, pig, 

 sheep, and goat ; and in them it gives attachment to strong muscles 

 which move the head on the trunk. It is called the paramastoid 

 process. 



In Crocodiles, Birds, and the three- toed Sloth, there are always ribs 

 attached to the cervical, or neck vertebrae, and in Crocodiles, Alligators, 

 and some other animals, there are always ribs attached to the lumbar 

 vertebrae. But these are not - normal to man. The human embryo, 

 however, always has a rib on each side connected with the seventh neck 

 vertebra. Ordinarily, before the fifth year it becomes blended with the 

 ordinary transverse process, but occasionally this rudiment goes on de- 

 veloping till it becomes a more or less perfect cervical rib. 



Lumbar ribs are also occasionally found. These supernumerary ribs 

 are no doubt due to arrested development. 



