ANATOMY OF VERTEBRATES. 143 



with, the 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 50 

 depends upon the circumstance of these bones constituting the 

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

 haemal 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, f suprascapulaire' to 50, and 

 f scapulaire' to 51, in both Fish and Crocodile ; but he did not per- 

 ceive or admit that the narrower relations of special homology 

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

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

 93, 50 and 51, a compound ' pleurapophysis,' in 52 a ( haemapophy sis,' 

 and in hs, the ( haemal spine,' completing the haemal arch. 1 



The scapulo-coracoid arch, both elements, 51, 5-2, 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 haemal arches. Viewed as a more robust hamial 

 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 vertebras of the cranium or in the 

 sacrum of the bird, 2 we proceed to examine the vertebra before 

 and behind the displaced arch, with the view to discover the one 

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

 no centrum and neural arch without its pleurapophyses from the 



1 The author of No. CLXXI, in criticising this conclusion, omits consideration of 

 the cartilaginous element, fig. 93, so : as it exists and required due attention, I 

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

 Fishes, 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 Pomoplate ' of the Crocodile, with the ' partie spinal del'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 the 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 lurks the fallacy of his criticism. CLXXI, 

 pp. 27, 28. The alleged difference of developement, at most one of direction of growth, 

 is futile. 



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



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

 of the vertebra ' to the ' ha?mapophyses and hasmal spine,' Dr. Humphrey makes 

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

 as being the hasm- not the pleur-apophysis. 



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

 and 159. 



