A Few Cases of Meristic Variation in the Common 

 Toad and an Isopod. 



BY 



Seitaro Goto. 



It is the purpose of this paper to note down a few cases of variation, that 

 have been brought to my notice during the students' dissection in my 

 laboratory, and to bring them, where possible, into connection with those 

 already published. 



Abnormalities in the skeleton of the Amphibia are not rare, and the 

 published cases down to 1S94 have been brought together by Eateson 

 I' 94, p. 124 et scq\ 



As an introductory to the cases concerning the vertebral column of 

 the common toad, I shall give a general description of a normal vertebral 

 column of this animal {Bufo vulgaris), and add a few facts which are of 

 importance in discussing the significance of the cases mentioned. 



The normal vertebral column of the common toad consists of nine 

 separate vertebrae and the urostyle. The first vertebra, or atlas, has no 

 transverse processes ; the centrum is well developed, and its anterior 

 surface bears a pair of large, somewhat hour-glass shaped, concave facets 

 for articulation with the occipital condyles. The epistropheus bears stout, 

 forwardly directed transverse processes. The third vertebra bears long, 

 stout, flattened transverse processes, which are in direct connection with the 

 supra-scapula. The fourth vertebra bears also long, stout transverse pro- 

 cesses, but they are not so flattened as those of the third, although longer. 

 The fifth, sixth, seventh, and eighth vertebrae all bear rather slender trans- 

 verse processes, which gradually diminish in size backwards. The ninth 

 vertebra is the sacrum, and is very stout, and its transverse processes are 

 as long as, or longer than, those of the third vertebra, and expanded into 

 a wing-like shape ; the centrum is bifid posteriorly, and bears two convex 

 facets for articulation with the coccyx. All the vertebrae from the second 

 backwards are procoelous. 



