THE THEORY OF THE VERTEBRATE SKULL. 287 



the abdomen of the head. The squamosal is the conjoined 

 scapula and ilium of the head ; the pterygoid, the clavicle ; the 

 hyoidean apparatus, the other pelvic bones. The jugal arch 

 represents the humerus, radius, and ulna ; the maxilla, the 

 hand; the premaxilla, the thumb; the teeth, the fingers. The 

 lower jaw represents the legs of the head ; the teeth the toes ; 

 and, of all imaginable hypotheses, the styloid processes are the 

 sacrum of the head ! 



Reasons, worthy of the name, for these identifications are 

 not to be found in the " Programm." Oken, having assumed 

 once for all, that, as the brain-case repeats the spinal canal, the 

 facial bones must repeat the other appendages of a vertebral 

 column and the limbs, seems to have troubled himself no fur- 

 ther about demonstration. What a bone should be, in order to 

 fit plausibly into his scheme, that it was at once settled to be — 

 an appeal to the " idea " dispersing all doubts. 



A few years later Oken modified his original conception so 

 far as to regard the nasal apparatus as a fourth vertebra. 



Whatever may be thought about the more speculative pas- 

 sages of the extract above cited from Oken's work, and of his 

 a priori conception of what a skull must be, it contains ample 

 evidence that he did, a posteriori and inductively, demonstrate 

 the segmented character of the bony brain-case; and had 

 nothing more ever been written on the subject, this great truth 

 would have remained as a splendid contribution to morphology. 

 But Oken greatly amplified the observational basis of his own 

 doctrine ; Spix took it up, in a modified form, and worked it out, 

 in his own way, through the series of the Vertebrata in his great 

 illustrated " Cephalogenesis," published in 1815 ; Bojanus did 

 the like in the pages of the " Isis," and in the "Parergon ' of 

 his splendid monograph, the "Anatome Testudinis ;" and, 

 finally, C. G. Carus developed the doctrine, as far as it conld 

 well go, both a priori and a posteriori, in his " Urtheilen des 

 Knochen unci Schalen-Gerustes," published in 1828 ; in which, 

 under the names of " Grund-form ' and " Schema," we have, 

 among other things, " archetypal ,: diagrams of the Vertebrata 

 generally, and of each vertebrate class. 



Under these circumstances, the following passage, extracted 



