312 



SCIENCE. 



[Vol. V., No. 115. 



tidal experts to determine the co-tidal curves 

 for Lincoln Sea, and Robesen and Kennedy 

 channels. 



The temperature of the surface sea-water was 

 carefully observed from October, 1882, to June, 

 1883. The temperature fell steadily from a 

 mean of 29.2° in October, to 29° in December, 

 and then rose steadily to 29.4° in June. The 

 ebbing tide (to the north) was from 0.1° to 

 0.2° colder than the flowing tide, and its mean 

 for December was 28.9°. 



The sounding of 133 fathoms and no bottom, 

 midway between Capes May and Britannia, is 

 significant of a different ocean along the north 

 coast of Greenland, from the shallow sea north 

 of Asia, North America, and Grinnell Land. 



Forty-eight swings, with accom panying time 

 observations, were made with a pendulum fur- 

 nished by the U. S. coast and geodetic survey. 

 The observations are now in the hands of Assist- 

 ant Charles S. Peirce for reduction and com- 

 parison. I regret that continued mental and 

 physical weakness have prevented more care- 

 ful and systematic treatment of these subjects. 

 This summary is now presented, as the imme- 

 diate future promises no better results from 

 my hands. A. W. Greely, U.S. army. 



FOOTPRINTS IN THE ROCKS OF 

 COLORADO. 



From a few tracks and signs, an Indian is 

 said to have inferred that at noon there had 

 passed by a white man, lame in the left foot, 

 blind in the right eye, dressed in gray, and 

 with a double-barrelled gun and a black dog. 

 With no attempt to rival the aborigines, nor 

 to name and classify, it is interesting to notice 

 some features of the footprints on four slabs 

 from St. Vrain Creek, Col., — the only ves- 

 tiges of animal life thus far reported from the 

 immense beds of triassic sandstones in the 

 eastern Rock} 7 Mountains. Three of the slabs 

 are in the museum of Iowa college, Grinnell, 

 Io. : the other, No. 2, has been sent to the 

 national museum. 



Slab No. 1, represented in the figure, with 

 two of the tracks on a larger scale, is some- 

 what like the rare horseshoe forms found in 

 Europe and in the Connecticut valley, in rocks 

 of the same age. No hoofed animal is sup- 

 posed to have existed at so early a period. 

 The shape has been attributed to a membrane 

 beneath claws, in this case a firm, flat pad, 

 if that be the explanation, and semicircular 

 within as well as exteriorly. In the three for- 

 ward tracks, the fore and hind feet coincided, 



making one impression. In four of the re- 

 maining tracks, the smaller fore-feet show a 

 crescent that coalesces with that of the hind- 

 foot. There is a rough, broken, irregular bulg- 

 ing of the rock in and behind the hollow of 

 the foot, dying away backward into the sur- 

 face. The great amount of this would suggest 

 that the animal was ascending a wet slope. 



The appearance of slab No. 3 is so like 

 No. 2 that they were probably one continuous 

 series. As seen in the figure, the larger im- 

 pression of the hind-foot mostly touches, and 

 once or twice somewhat overlaps, that of the 

 fore-foot, which is evidently such because its 

 position varies relatively to the former. It 

 has a wide angle from the line of progression. 

 In the last (uppermost) left feet, the fore-foot 

 repeats its print, though at first glance it looks 

 like a jointed toe. All the impressions are 

 simple ovals (ellipses) , deepest in the centre ; 

 and several, as in the larger separate figure, 

 have a shallow ear-shaped impression on the 

 inner forward border, which, in two, shows 

 slight lengthwise wrinkles. The left-side 

 tracks are less perfect, as if the right feet 

 pressed on a lower, wetter part of the ancient 

 beach. 



In No. 3 there was an inch space between 

 the heels in passing each other ; in No. 1, little 



Third left feet. 

 Scale I. 



SLAB NO. 1. 



Average stride, 8| inches; width of trackway, A\ inches. 

 Scale, 1-12. 



or none. The animals must therefore have 

 had an erect habit, not the dragging move- 

 ment, with horizontally extended legs, of 

 ordinary reptiles, if reptiles they were. 



