24 SCIENCE PROGRESS 



Carso Triestino, are discussed by Dr. d'Erasmo in Boll. Soc. 

 Adriat. Set. Nat. vol. xxvi. pp. 45-88, in a manner chiefly 

 interesting to systematists. The same remark applies in an 

 even greater degree to a paper by Mr. L. Neumayer in the 

 Palceontographica (vol. lix. pp. 251-88) on the comparative 

 anatomy of the skull in Eocene and modern Siluridce. 



Two papers have been published during the year on the 

 nature of those remarkable flat spiral structures, armed on the 

 convex border with powerful teeth, described under the names 

 of Edestus, Helicoprion, etc, which have long been a puzzle to 

 ichthyologists, some of whom have regarded them as highly 

 modified dorsal spines of sharks, whilst others consider that 

 they pertain to the mouth. The first of these is an English 

 translation of a paper by Mr. A. Karpinsky in Bull. Ac. Sci. 

 St. Pe'tersbourg, 191 1, pp. 1 105-21, briefly mentioned in my 

 review for that year. The main object of this paper, of which 

 the translation is published in Verh. K. Min. Ges. St. Pe'tersbourg, 

 vol. xlix. pp. 69-94, is to show that the view held by Dr. O. P. 

 Hay and others that these organs are dorsal spines is untenable 

 and that they are really appendages of the mouth. To this 

 view Dr. Hay {Proc. U.S. Nat. Mus. vol. xlii. p. 31) is, how- 

 ever, himself a convert, as the result of the examination of a 

 specimen discovered about eighteen years ago in the Coal 

 Measures of Iowa. This specimen, which is double, comprises 

 an upper and a lower element, both of which are bilaterally 

 symmetrical and appear to have been produced in front of the 

 mouth of the shark in such a manner that one worked against 

 the other. Their shafts seem to have been developed by the 

 consolidation and fusion of a median row of teeth, which 

 gradually become worn away in the fore part of the series in 

 the usual shark-fashion but the bases of which form the shaft. 1 



NOTE: GIANT TORTOISES AND THEIR 

 DISTRIBUTION 



In my article on "Giant Tortoises and their Distribution," 

 Science Progress, October 19 10, vol. v. pp. 302-17, reference 



1 Since this article was set up, several other palaeontological papers and 

 memoirs have come to hand (notably a continuation of Prof. W. B. Scott's des- 

 cription of the Santa Cruz fauna), which it was found impossible to notice. 



