IN THE LIMBS OF MAMMALIA. 53 



succeeding haemal arch which supports the penis, the longitype of the tongue, the pleura- 

 pophysial elements of the arch being deficient. 



In most mammalia, but by no means in all vertebrates, the pubic bones support the 

 male organ of generation; the ischiatic bones are certainly the posterior of the two pelvic 

 arches, and may reasonably be supposed to represent the hyoid bone ; at any rate, despite 

 the vast teleological discrepancy, the anterior portion of the head seems, so far as morphol- 

 ogy is concerned, to be the fixed longitype of the more or less movable series of vertebrae 

 behind the fixed pelvis. 



Having thus admitted a general homology between these two extreme regions of the 

 body, we must wait for further evidence to show first, whether there is really any such spe- 

 cial homology as at first appears probable, and if so, whether the clavicle and coracoid repre- 

 sent the ischium and pubis respectively, as the bones alone would indicate, or whether, regard- 

 ing also the fleshy parts, the hyoid bone is the antitype of the ischium, and the clavicle that 

 of the pubis, the coracoid being merely a process like the marsupial bone of the mammals 

 characterized thereby. 



The alimentary canal with its appendages next merits our attention. 



The former is embryologically and morphologically a simple straight tube, with an an- 

 terior opening in the head and a posterior one in the pelvis. In the adult state, however, 

 this tube is always more or less enlarged and convoluted, to afford a reservoir of the size, 

 and an absorbent surface of the extent required by the nature of the food consumed; but 

 all such modifications are purely teleological, and only conform to the general arrangement 

 which assigns to the organs of nutrition a region below that in which are the organs of the 

 motive forces, and above that devoted to generation. 



There is at first but a single anterior and posterior opening, but the former is generally 

 and the latter in mammalia afterward, divided into a superior and an inferior opening ; the 

 nasal and oral, the anal and genital orifices, by transverse bands which bear the names of 

 upper lip and perinasuni. 



With one exception, all sexual diversity is teleological, that is, resulting from a difference 

 in the size or shape of parts which exist alike in both sexes. The exception is in the case 

 of the ovary and the testis, which, being entirely distinct in every respect, constitute the 

 only morphological difference between the two sexes ; a true hermaphroditism is, of course, 

 impossible, except between the two sides of the body; and this would be a positive condi- 

 tion, while all the so-called cases of hermaphroditism are merely negative and doubtful 

 states. 



In the anterior region, enumerating from above, that is, from the vertebral column 

 downward, the parts are, the nose, or anterior nares, the upper lip, the mouth, the tongue, 

 and the chin; posteriorly, the anal opening, the perinceuiu, the vaginal opening, the penis or 

 the clitoris, and the pules. The morphological correspondence is as evident as is the tele- 

 ological difference. 



There are two principal diverticula of the alimentary canal, the lungs and the urinary 

 bladder ; the former open forward and the latter opens backward, and their outlets are be- 

 tween the pharynx or mouth and the tongue, anteriorly, and between the vaginal open- 

 ing and the clitoris posteriorly. There is a physiological relation also, for the bladder is a 

 dilatation of the internal portion of the allantois, which was the fcetal organ of respiration. 

 The thyroid gland is in relation with the larynx much as the prostate gland is with the 

 neck of the bladder; but the former has no excretory duct as has the latter. 



