NO. I 



SMITHSONIAN EXPLORATIONS, I919 



21 



their comparative study one of much interest. Important new mate- 

 rial was obtained which is added to the collection of echinoderms 

 deposited in the National Museum. Mr. Springer's monograph of 

 the Crinoidea Flexibilia, now being published by the Smithsonian 

 Institution, has been printed and only awaits binding to be ready 

 for distribution. It will be in two quarto volumes, one of them con- 

 taining 79 plates. 



The Section of Vertebrate Paleontology has been unable to imder- 

 take any field explorations during the past year, and the time of the 

 staff has been largely employed in preparing and mounting for 

 exhibition material otherwise obtained. 



Fig. 20. — View of small portion of Huffman Conservancy dam near 

 Dayton, Ohio, showing excavation in which the largest trilobite was found. 

 Photograph by courtesy of Arthur E. Morgan, chief engineer. 



Through the acquisition from the veteran collector of fossils, 

 ]\Ir. Charles H. Sternberg, of an excellent skeleton of the large 

 swimming lizard l^ylosaitnis dyspelor and a skull of the primitive 

 horned dinosaur Monocloniiis, an interesting addition to the exhibi- 

 tion collection was made. Figure 21 shows the Tylosaurus skeleton 

 in process of being mounted for exhibition by Mr. N. H. Boss. It 

 will form a panel, in half relief, and will occupy the wall space in 

 the northeastern part of the main exhibition hall of fossil vertebrates. 

 The diving pose given the skeleton was largely determined by the 

 position of the articulated tail as found in the ground. 



