ANATOMY OF VERTEBRATES. 143 



with tlic similarly numbered constituents of the same arch in 

 Fishes — though masked, not only by modifications of form and 

 proportion, but even of very substance, as in the case of so — 

 depends upon the circumstance of these bones constituting the 

 same essential element of the archetyjial skeleton, viz. the fourth 

 hremal arch, numbered pi, 52, in fig. 17. For although in the pre- 

 sent instance there is superadded to the adaptive modifications 

 above cited the rarer one of altered connections, Cuvier does not 

 hesitate to give the same names, ' suprascapulaire' to 50, and 

 ' scapulaire' to 5i, in both Fish and Crocodile ; but he did not pcr- 

 cfAxe or admit that the narrower relations of special homology 

 were a result of, and necessarily included in, the Avider law of 

 general homology. According to the latter law, we discern in fig. 

 93, 50 and 5i, a compound ' pleurapophysis,' in 52 a 'hajmapophysis,' 

 and in hs, the ' ha3mal spine,' completing the haemal arch.' 



The scapulo-coracoid arch, both elements, 6i, 52, of which 

 retain the form of strong and thick vertebral and sternal ribs in 

 the Crocodile, is applied in the skeleton of that animal over the 

 anterior thoracic hajmal arches. Viewed as a more robust hreraal 

 arch, it is obviously out of place in reference to the rest of its 

 vertebral segment. If we seek to determine that segment by the 

 mode in which we restore to their centrums the less displaced 

 neural arches of the antecedent vertebra? of tlie cranium or in the 

 sacrum of the bird,^ we proceed to examine the vertebra; before 

 and behind the dis2")laced arch, with the view to discoA-er the one 

 wdiich needs it, in order to be made typically complete. Finding 

 no centrum and neural arch without its pleurapophyses from the 



' The author of No. clxxi, in criticising this conclusion, omits consideration of 

 the cartilaginous element, fig. 93, 60 ; as it exists and required due attention, I 

 was led to regard it as tlie homologue of the ossified element, figs. 81, 85, 50, in 

 Eishes, and as being part, one might say, half, of the pleurapophysis. No anatomist has 

 impugned such determination of the special homology of the ' lame cartilagineuse 

 du bord spinal de I'omoplate ' of the Crocodile, with the ' partie spinal de I'omoplate ' 

 of the Frog, and with the ' os surscapulaire ' of the Fish. Now the latter is the 

 homotype of the proximal half of the compound pleurapophysis of the pelvic arch, 

 of which tlie part called ' ilium ' answers to the part called ' scapula.' There remains, 

 therefore, for Dr. Humphrey's consideration, the serial and general homologies of the 

 ' suprascapula ; ' in the omission of which lurlcs the fallacy of his criticism, clxxi, 

 pp. 27, 28. Tlie alleged difference of devclopement, at most one of direction of growth, 

 is futile. 



A ' htemal arch ' having been defined as including the ' pleurapophysis ' as well as 

 'hajmapophysis,' by altering the meaning of the term and restricting the ' haemal parts 

 of the vertebra ' to the ' hajmapophyses and haamal spine,' Dr. Humphrey makes 

 ground for pronouncing the part of the haemal arch, 50 and .51, in figs. 81 and 92, 

 as being the hxm- not the pleur-apophysis. 



^ See 'On the Archetype and Homologies of tlie Vertebrate Skeleton,' pp. 117 

 and 159. 



