VARIATION IN TOAD AND ISO POD. 



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parts of the ninth. The posterior surface of the centrum presents two 

 convex articular facets, as in the normal sacral vertebra. The neural arch 

 is narrower from before backwards than in the normal sacral vertebra, and 



A. Dorsal view. Cut 4. B. Ventral view. 



there is a slit-like space left between the ninth and tenth vertebrae on the 

 dorsal side. The ninth intervertebral foramina are almost round and 

 slightly smaller than the eighth. 



Case 5. Bufa vulgaris, <£ . Sacrum formed by the tenth vertebra. 

 (Cut. 5.) 



The ninth vertebra is only very slightly larger than the eighth. The 

 transverse process of the right side is very slightly Lmger than that of the 

 eighth, but that of the left is longer, and much broader and flattened, and 

 recalls that of the normal sacrum. The posterior surface of the centrum 

 presents a kidney-shaped articular facet ; and it is to be mentioned in this 

 connection that, in this skeleton there appears to be a certain tendency in 

 the posterior surface of the centrum of some of the more anterior vertebrae 

 to become lobed or double. Both the anterior and posterior zygapophyses 

 are well developed and are similar in all respects to those of the typical 

 vertebra. There is, however, an irregular, indistinct longitudinal groove on 

 the ventral surface of the centrum. 



The tenth, or sacral vertebra is very large and is similar to the normal 

 sacrum, except in a few particulars consequent to the transformation of the 



