1871. 



1& 



[Wilder. 



like a real homology has ever been shown to exist between the inter- 

 nal organs of the dorsal and ventral regions; and the development 

 of the ovum results in a differentiation of dorsal from ventral, which is 

 not suggestive of any such homologous relation as is so apparent be- 

 tween right and left, or between cephalic and cereal, regions. 



This important question will be hereafter indicated as one of the 

 problems to be solved. At present, I will only state my conviction 

 that the complete vertebrate animal con- 

 sists of two individuals of different sexes, 

 placed face to face; 1 there then results 

 a true antitropical homology in all three 

 directions corresponding with the three 

 diameters of a solid ; a lateral homology or 

 "platetropy" between two right and left 

 halves of this compound individual, a lon- 

 gal homology or "meketropy" between its 

 cephalic and cereal regions, and a vertical 

 homology or "hypsetropy" between the 

 dorsal regions of the two individuals and 

 between the ventral regions in like man- 

 ner, as in fig. 2. Such a homology of 

 three directions might be exemplified in Fig. 2. 



a perfect double monster by "anterior duplicity," described and 

 figured as "Zipophage" by St. Hilaire, 235, PI. xiv, fig. 3. 2 



PSEUDANTITROPY. 



Polar relation of bach and belly, Oken, 285, Par. 2093, (1810). — 

 Dorso-ventral symmetry, Macl., 22, 667, (1849). — Anteroposterior 

 symmetry, Pitt., 293, 851, (1850). — Tergality (in part) , Ag., (Rem. on) 

 298, 279, (1861).— Dorso-ventral polarity, Dana, 218, 351, (1863).— 

 Vertically (in part), Wild., 45, 14, (1865).— Bipolar ity, Clark, 211, 

 265, (1865). — Vertipolar homology (in part), Wild., 58, Lect. 1, 

 (1867).— Vertical homology, Miv., 278, 120, (1870). — Dor so-abdominal 



1 Prior suggestions of this idea are contained in Par., 2955 of 285: but indeed, 

 there are few morphological ideas of the present day, germs of which cannot be 

 found in the extraordinary work here cited ; and although it is not altogether satis- 

 factory to find one's most valued conceptions thus ambiguously anticipated, no 

 worker in homology should try to lessen Oken's just fame, or hold any other than 

 the opinion which one of his greatest pupils has given us concerning his work. 

 Agassiz, 200, and 201, chap, ill, Sect. v. 



2 This would be a Dicephatus tetrabrachius tetrapus, in the nomenclature of 

 Fisher, 229,61. 



