November 22, 1901.] 



SCIENCE, 



795 



wider and rougher on the west side of the 

 valley than on the eastern. This is par- 

 ticularly true of those later than the first, 

 for they are formed on a quite smooth 

 plain. The first is much influenced by pre- 

 glacial topography. Moreover the western 

 sides of the loops are apt to be at lower alti- 

 tudes. In seeking for an explanation for this, 

 we find nothing more satisfactory than the 

 fact that the maximum diurnal temperature 

 is uniformly considerably higher after noon, 

 hence the western half of an ice l&be will 

 receive more heat and consequently be more 

 active, i. e,, move faster, bring more debris, 

 melt more rapidly, be more apt to detach and 

 bury more ice blocks. The lower altitude 

 may result from the melting back of the ice 

 farther on a concave surface, such as is 

 apt to be left by the former ice sheet. A 

 corollary of this general proposition is 

 that in the northern hemisphere the south- 

 ern side of an east- or west-flowing glacier 

 will tend to exhibit similar phenomena for 

 a similar reason, viz., because of the south- 

 ern position of the sun. Instead of curving 

 such glaciers toward the north, as argued 

 several years ago in one of our prominent 

 scientific journals, it will rather tend to 

 quicken the motion in the ice toward the 

 south, though at the same time, because of 

 greater melting, it may not widen the ice, 

 but the contrary. If the debris transported 

 is abundant it may turn the course of the 

 glacier northward, somewhat as the deposi- 

 tion of sediment in a delta or an alluvial 

 fan may divert the stream which forms it. 

 Of course the influence here recognized is 

 not all-powerful, but may be counteracted 

 in certain cases by other conditions. 



' On Campodus, Edeshis, Helicoprion, Acan- 

 thodes, and other Per mo- Carboniferous 

 '.Sharks' : C. R. Eastman. 



The genus Campodus, known only by 

 fragmentary remains from the Coal Mea- 

 sures, was shown by St. John and Worthen, 

 and later by Max Lohest, to have possessed 



a typical Cestraciont dentition. The re- 

 searches of these authors were based upon 

 a unique example of the left ramus of the 

 lower jaw, from which the anterior and 

 posterior extremities were missing. Two 

 specimens are now known, belonging re- 

 spectively to the Museum of Comparative 

 Zoology at Cambridge and the State Uni- 

 versity of Nebraska, which exhibit the 

 symphysial series of teeth and incidentally 

 throw new light on the relations of Edestus, 

 Helicoprion and the like. In one jaw of 

 Campodus, presumably the lower, there 

 was one arcuate, median azygous series of 

 symphysial teeth, opposed to which in 

 (presumably) the upper jaw were two 

 corresponding series separated by a slight 

 interval. As successional teeth were de- 

 veloped the functional ones became coiled 

 in a regular arc like Edestus, with the cor- 

 onal buttresses directed inward (posteri- 

 orly). The complete whorls of Helicoprion 

 are believed to represent a more advanced 

 stage of an entirely homologous dental 

 structure. A new and very large species of 

 Acanthodes, represented by a pectoral fin, 

 numerous spines and shagreen, was reported 

 from the Coal Measures of Mazon Creek, 

 Illinois, and reference made to the occur- 

 rence of Phoehodus in the Keokuk Lime- 

 stone of Iowa and Permian of Nebraska. 

 The larg6 variety of Ctenacanthus spines 

 occurring in the Kinderhook Limestone 

 of Iowa fall into two principal categories, 

 one long and slender and gradually taper- 

 ing, the other short and blunt. These are 

 probably to be correlated with the first and 

 second dorsal fins of the same individual, 

 instead of being regarded as distinct species. 



* Note on Certain Copper Minerals ' : 

 Alexander N. Winchell. 



Chalcopyrite has been found more than 

 once as an accidental product in metal- 

 lurgical operations, but bornite has never 

 been described as formed in the same way, 

 nor as produced artificially by sublimation. 



