Diversity in the Scutes of Chelonia. 55 



As there were very few abnormal turtles, and since all are of 

 approximately the same age, the table may conveniently be abbre- 

 viated. First the abnormal turtles are listed, and then the normal 

 turtles in several- classes according to the plan of the marginals. 



The abnormalities are: C5 represented by 2 scutes (4 specimens), 

 nuchal paired (119), JSTS incompletely divided transversely (120), 

 and, supernumerary marginal (121). 



All of the common marginal plans occur, but 13-13 largely pre- 

 dominates (40 specimens). 



As the nest was never disturbed during the period of incubation 

 (except at the start) it cannot be stated whether or not there was 

 much swelling of eggs with consequent pressure between them. This 

 undisturbed natural nest yielded a far greater proportion of normal 

 turtles than any nest transplanted into the ground at the laboratory. 



Table IX. On account of the possibility of the pressure in 

 natural and artificial nests having some effect on the method of 

 growth of the scutes it was desired to remove some eggs from such 

 conditions. Therefore, a number of eggs from two or three nests 

 were placed on the shelves of the incubating box described above. 

 The eggs were surrounded and covered by a very small amount of 

 moist sand, but not sufficient to offer any considerable resistance to 

 the expansion of the egg in any direction. On account of the poor 

 success of the eggs transplanted into the ground, the incubator was 

 frequently drawn on for embryological material, especially to fill 

 the gaps in the earlier stages. Table IX, therefore, includes only 

 18 embryos — all from a single original nest. The number is entirely 

 inadequate for conclusion, tut it was interesting to find that only a 

 smgle specimen was abnormal (by the possession of a 6th neural — 

 cf., Fig. Y9). The marginals display exceptional uniformity. In 

 the three youngest specimens they were not distinct, in one the plan 

 is 13-12, but in all the others the plan is 12-12. It is possible that 

 the eggs from this original nest would have developed with as much 

 uniformity under other conditions. 



The table can conveniently be abbreviated. 



