S Eobert E. Coker. 



Xewmann ('06), who has made the most extended, study of the 

 abnormalities of scutes and plates, lays much stress on the phylo- 

 genetic significance of scutes, but departs materially from Hay in 

 that he regards Dermochelys as out of the line of descent of The- 

 cophorous turtles, as "an abnormal and perhaps highly specialized 

 forin." This is a position which Baur held and zealously defended 

 in a series of papers from 1886 to 1896 ('86, '88 a and b, '89 a and 

 b, '90, '96). 1 The view was adopted by Case ('97). 



]S[ewmann bases his view primarily on a study of the assumed 

 atavisms and of the color patterns of the carapace, but in part also 

 on the comparison of the different scute-plans normal for different 

 species of turtles. The keynote of his paper is expressed in the 

 words: "Careful study has convinced me that these abnormalities 

 are to be considered not as meaningless anoiualies but as examples 

 of systematic atavism in the sense of de Vries. From this stand- 

 point it seems possible to throw some light on the phylogeny of 

 CJielonia." 



These abnormalities as ISTewmann regards them are reversions, not 

 to the keel plan of Dermochelys-like turtles, but to a plan essentially 

 similar to that found in the "tail-trunk" of modern Chelydra, where 

 he believes the primitive condition of the scutes is most nearly pre- 

 served. There he finds seven principal rows of scutes and, alternat- 

 ing with them, seven subordinate rows of smaller or less regular 

 scutes. To homologize these with the series of scutes in the carapace 

 and plastron, — the seven principal rows correspond to neural (one), 

 costal (two), marginal (two), and plastral (two) ; these rows are 

 found in all carapaces (except those of the Trionychoidea) . The 

 seven subordinate rows correspond to (a) paired neuro-costals (lost 

 in all turtles) ; (b) paired supramarginals (preserved normally only 



^Newmann's statement ('06, p. 99) that Baur with Hay regarded Dermoch- 

 elys as the ancestral form, seems based on a preliminary note by Baur dated 

 October 6, 1886, and appearing in the American Naturalist for January, 1887 

 Subsequent to the writing of this preliminary note, even prior to its appear- 

 ance, Baur had discarded the old and generally accepted view, so that his 

 complete paper, dated October 26, and appearing in the Zoologische Anzeiger 

 for November, 1886, announced unmistakably the view which he thereafter 

 maintained. 



