THE "STOMACH STONES" OF REPTILES

    Gastroliths have been known to occur, mingled with the remains of extinct reptiles, for many years and much attention has been called to them in the pages of SCIENCE and elsewhere, especially by Mudge, Seeley, Williston, Eastman, Wieland and Brown. Interesting parallels have been cited among several living vertebrates. There has been some contention that the stones were taken for the purpose of a "gastric mill," but they were in part at least accidental. There seems to be some evidence for the conclusion that the plesiosaurs, at least, selected stones for this purpose, though this may have been more accidental than we think. Recently there has been brought to my attention by Mr. Edward Taylor, of the University of Kansas, au interesting case of stone swallowing by a lizard,. Phrynosoma cornutum Harlan. Only a single specimen is at hand for the data, but it is of sufficient interest in connection with identical habits among fossil reptiles to be recorded. The horned "toad" in question is a very large adult female collected by the late Dr. F. H. Snow in the Magdalen Mountains of New Mexico. In the stomach were twenty large, somewhat abraded stones of a rock which resembled lava. Some of the stones are very large, for the size of the animal, measuring nearly a third of an inch in diameter. There were also in the stomach about 200 of the large red ants, of an undetermined species, which make the large mounds so common to the western traveler. The animal had undoubtedly picked up the stones with the ants from the top of the mound and the association is probably accidental. That they served the purpose of a "gastric mill " once inside the digestive canal can not be doubted, whether the animal willed or no.

    In this connection it may be of interest to the readers of these pages to call attention to some large Cretaceous sharks which have, within the past few months, been received at the University of Kansas Museum. In one specimen [KUVP 68979], consisting almost entirely of scattered vertebral cartilages, there are associated many hundreds of greatly abraded, very smooth and polished stones of white and black quartzite.

378                            SCIENCE             [N. S. Vol. XXXV. No. 897

     That they belong with the shark can not be doubted on account of the association. The pebbles resemble to a great extent those figured by Dr. Williston some years ago as occurring with a pleisosaur [sic]. Another, nearly complete skeleton of a large shark, Isurus mantelli Ag., [KUVP 247] has preserved the larger part of the cranial cartilages. The sharks will shortly be described in detail and further reference need not be made to them here.

                                                                 Roy L. Moodie

THE UNIVERSITY OF KANSAS,

    January 26, 1912