14 ABNORMAL CONDITIONS OF THE AXIS. 



innominate bones are less developed, so that the median leg was 

 probably either rudimentary or wanting. 



The accessory innominate bones consist chiefly of the tuberosities 

 and posterior rami of the ischia ; these are united below by os- 

 sified fascia, which extends to the arch of the pubis. There are 

 two penes, urethree, and bladders, and but two testes. Each blad- 

 der has a single ureter opening into its outer side. The right 

 kidney is reduced to a hard fibrous button-shaped mass, about three 

 quarters of an inch in diameter ; the right bladder is much thinner 

 than the left, and its cavity is occupied by a fungous mass of 

 granulations. The muscles of the bulbs of the urethrae arise partly 

 from the additional and partly from the normal pelvic bones. The 

 right prostate is very small, and the urethra of this side is im- 

 pervious where it passes between the pelvic bones. 



b. Schizorhachis. 



Under this term all cases of posterior dichotomy of the spinal 

 column have been included, except those in which the mal- 

 formation extends to the head and appears externally, and 

 those already described as dipygus. Dichotomy almost always 

 extends to the occiput, and usually affects the basioccipital bone 

 slightly. A single preparation shows dichotomy of the lumbar 

 region only. 



a. Unsymmetricdl Schizorhachis. 



68. The posterior portion of a foetal Pig, with posterior dicho- 



tomy of the spinal column commencing in the lumbar 

 region. The right half of the double axis and its limbs 

 are much smaller than the left. This preparation has 

 been dissected to show the viscera. 



The intestine and stomach are drawn up. There are two uri- 

 nary bladders ; that belonging to the accessory axis has two ureters 

 and two minute kidneys. There is a large suprarenal capsule on 

 the right side. The left axis has only a single, much elongated 

 kidney on its left side. The aorta bifurcates to supply the second 

 axis. 



/3. Symmetrical Schizorhachis. 



69. A foetal Pig with dichotomy of the whole spinal column and 



four distinct anterior extremities. The thoracic and ab- 

 dominal cavities have been opened to show the heart and 



