Lhap. VI. 



Affinities and Genealogy. 



161 



served tlicm as formidable weapons. At a much earlier period 

 the uterus was double; the excreta were voided through a cloaca; 

 and the eye was protected by a third eyelid or nictitating mem- 

 brane. At a still earlier period the progenitors of man must have 

 been aquatic in their habits; for morphology plainly tells us that 

 our lungs consist of a modified swim-bladder, which once served 

 as a float. The clefts on the neck in the embryo of man show 

 where the branchiae once existed. In the lunar or weekly re- 

 current periods of some of our functions we apparently still retain 

 traces of our primordial birthplace, a shore washed by the tides. 

 At about this same early period the true kidneys were replaced 

 by the corpora wolffiana. The heart existed as a simple pulsating 

 vessel; and the chorda dorsalis took the place of a vertebral 

 column. These early ancestors of man, thus seen in the dim 

 recesses of time, must have been as simply, or even still more 

 simply organised than the lancelet or amphioxus. 



There is one other point deserving a fuller notice. It has long 

 been known that in the vertebrate kingdom one sex bears 

 rudiments of various accessory parts, appertaining to the re- 

 productive system, which properly belong to the opposite sex ; 

 and it has now been ascertained that at a very early embryonic 

 period both sexes possess true male and female glands. Hence 

 some remote progenitor of the whole vertebrate kingdom appears 

 to have been hermaphrodite or androgynous. 26 But here we 

 encounter a singular difficulty. In the mammalian class the 

 males possess rudiments of a uterus with the adjacent passage, 

 in their vesiculae prostaticse ; they bear also rudiments of 

 mammae, and some male Marsupials have traces of a marsupial 

 sack. 27 Other analogous facts could be added. Are we, then, to 

 suppose that some extremely ancient mammal continued andro- 

 gynous, after it had acquired the chief distinctions of its class, 

 and therefore after it had diverged from the lower classes of the 

 vertebrate kingdom ? This seems very improbable, for we have 

 to look to fishes, the lowest of all the classes, to find any still 

 existent androgynous forms. 28 That various accessory parts, 



26 Tins is the conclusion of Prof. 

 Gegenbaur, one of the highest au- 

 thorities in comparative anatomy; 

 see ' Grundziige der vergleich. Anat.' 

 1870, s. 876. The result has been 

 arrived at chiefly from the study of 

 tha Amphibia ; but it appears from 

 the researches of Waldeyer (as 

 quoted in 'Journal of Anat. and 

 Phys.' 1869, p. 161), that the sexual 

 organs of even " the higher verte- 



" brata are, in their early condition. 

 " hermaphrodite." Similar views 

 have long been held by some authors, 

 though until recently without a 

 firm basis. 



27 The male Thylacinus offers the 

 best instance. Owen, ' Anatomy of 

 Vertebrates,' vol. iii. p. 771. 



28 Hermaphroditism has been ob- 

 served in several species of Serranus, 

 as well as in some other fishes,; 



