Diversity in the Scutes of Clieloiiia. 49 



against the sand, yet the pressure among those that developed was 

 such that they lost their spherical shape and were somewhat flattened 

 on the sides where they pressed against other eggs. Some of this 

 flattening was lost before the photograph was taken ('06, PI. XX., 

 Fig. B). The possible influence of such a factor as this inter- 

 pressure of eggs in the production of abnormalities of various kinds 

 is not to be ignored. The indirect results of localized pressure on 

 the developing embryo of other animals is well known, especially 

 through such work as that of Spemann in the production of double- 

 headed embryos and ''cyclopean defects." It may not be a coin- 

 cidence that two ^'cyclopean" embryos developed in the nest just 

 referred to and that almost all of the turtles were abnormal in scutes, 

 and some in still other respects. 



Explanation, of Tables. 



There are four main tables (VI to IX). Table VI includes em- 

 bryos from a single nest obtained in 1903. No further observa- 

 tions were made until 1905. Table VII includes tlie embryos and 

 newborn from various artificial nests in the ground, and this table 

 has several subdivisions (A-E) in or(k»r to keep separate the turtles 

 from difterent original nests. In this way, the degree of diversity in 

 turtles of the same brood may be noted. Table VIII is based on 

 new-born turtles from a natural nest that was not disturbed. 

 Finally, in Table IX are turtles which developed in the incubator, 

 where crowding was provided against. 



The tables have essentially the same form as those in the preced- 

 ing part of the paper. The number of scutes in a series is indicated 

 only where abnormal, or, if normal in number but abnormal in 

 plan, the normal number is \^Titten in italics. The number of mar- 

 ginals, however, is always indicated since it cannot be said that 

 either 12 or 13 is abnormal. Thirteen on each side, 12 on each side, 

 or 12 on one side, 13 on the other — each of these plans is common. 

 For brevity they are referred to as the 13-13 plan, 13-12 plan, 12-13 

 plan, or 12-12 plan, the number given first being in each case that 

 of the left side. These plans may be seen, respectively, in Figs. 

 «3, 58, 72, and 52. 



