Diversity in the Scutes of Chelonia. 3 



scutes of the carapace. Longer acquaintance with a number of indi- 

 viduals of this species that were kept under observation at the 

 Fisheries Laboratory at Beaufort, ISForth Carolina, and with the 

 eggs, embryos, and young of the loggerhead sea-turtle Thalassochelys 

 caretta, made apparent a wide diversity in many respects. Among 

 the characters in which the turtles and eggs manifested striking indi- 

 vidual differences, we may mention shape and size of eggs and of 

 young, shape and size of head, shape of carapace, depth of body, 

 color pattern, boldness, habits of feeding and of hibernating and of 

 moulting, rate of growth, etc. It seemed that a diversity in respect 

 of scutes and plates was no more than one would expect in view of 

 the diversity shown in so many other respects. The aphorism that 

 no two individuals are exactly alike would seem to apply with pre- 

 eminent fitness to certain species of turtle. 



JSTevertheless, there are certain features of these "'abnormalities" 

 which the observer cannot but be impressed with, and which seem to 

 suggest some special significance. These features are: 



1. The frequent recurrence of certain more or less regular scutes 

 in definite positions. 



2. The striking correspondence of recuri'ing abnormal elements 

 of one species to those of another, and sometimes to normal scutes of 

 other species. Thus — 



(a) In 31 specimens of new-born gTeen turtles* 44 different 

 abnormalities were noted, but these were reducible to 11 

 types; or, to omit variations which occurred not more than twice 

 and are possibly coincidences, we have 39 abnormalities of 7 types. 

 The most anterior scute of the plastron, the normally unpaired inter- 

 gular, was in 6 specimens represented by a pair of scutes, and in 

 9 other specimens was partially divided. This scute occurs in few 

 genera, but in the normal conditions of Macroclemmys and of Chelys 

 (Gadow, '01, p. 325), there is found in this position a pair of 

 scutes. 



(b) In 3 specimens of the same lot a rectangular scute appeared 

 in the neural series between the normal fourth and fifth shields. An 

 almost exactly similar scute occurs twice as the only abnormality of 

 dorsal scutes noted in 4 specimens of Thalassochelys (Colpochelys) 



*See author's previous paper, '05a, p. 23. 



