Twenhofel and Dunbar — Nodules with Fishes. 159 



and the other shale, likewise obtains. At this locality a single 

 nodule like those which contain the vertebrates at Lawrence, 

 was found. It was about one-half inch in diameter and con- 

 tained nothing. The same sequence was found near the village 

 of Vinland, about ten miles south of Lawrence, but no verte- 

 brate nodules appear to be present. At this locality there is a 

 thin bed of coal a few feet above the limonite nodule band. 

 Traced northeastward, the sequence is the same near the village 

 of Tonganoxie and three nodules were found in the thin shale 

 just above the limestone. None, however, contained anything. 



Description of the Xodules. — The nodules are generally of 

 a gray color, with a granular surface, similar to that which 

 they would have, were they made of lime and sand. In shape 

 they vary from spherical to oblong, and are generally of regu- 

 lar proportions ; but some are quite irregular. A few are 

 slender elongate. The spherical shape is the most common, 

 but the oblong ones carry the better fossils. They appear to 

 have silica as their chief component, but a considerable per- 

 centage of lime is also present. 



Some of the oblong nodules are as much as two inches in 

 length, while a few of the round ones are not more than one- 

 half an inch long. The diameters of the average nodules 

 vary from three-fourths to one and one-fourth inches. The 

 outside usually affords no indication of the contents ; but a few 

 have been collected with the fossils protruding, one having a 

 piece of petrified wood projecting for fully one-half inch. 

 That the shape to a large extent was determined by the 

 inclosed bone is indicated by the fact that slender nodules con- 

 tain long bones, while skulls are usually inclosed in those 

 which are oblong. 



About one foot above the vertebrate zone is another layer 

 in which the nodules have an elongated, lenticular shape, 

 and are composed of impure limonite. They vary in length 

 from one to four inches, are frequently hollow, and contain no 

 fossils. 



Abundance of Nodules. — In order to determine the abun- 

 dance and distribution of the nodules, a space with an area of 

 fifty-six square feet was cleared and the nodules carefully col- 

 lected. From this space were obtained two hundred and 

 thirty-five, sixty of which contained vertebrate remains. The 

 nodules are unequally distributed, and appear to be most abun- 

 dant in the depressions of the limestone. From one square 

 foot as many as a dozen have been collected, while from 

 another area of equal size not one has been obtained. Unequal 

 distribution of fossils also occurs, the greatest number of those 

 having any value having been collected in one part of the 

 outcrop. 



