408 



ANNUAL REPORT SMITHSONIAN INSTITUTION, 1961 



Figure 1. — Partial pattern of the way in which the appendages are attached to trilobite's 

 body is shown in view of the animal's underside from restoration by St^rmer. Approx. 

 x2. 



drawing and to the distance between successive sections. Each 

 outlined wax sheet was then cut out and the sheets put together to form 

 an enlarged model of the original specimen. The reconstruction (fig. 

 1) based on these models gives an idea of the great amount of detailed 

 information provided by St0rmer's work. This new knowledge, com- 

 bined with a restudy of all previously discovered material, has resulted 

 in a major advance in our understanding of trilobites. 



The reconstruction of the imderside of the body shows the large 

 plate (or hypostome) which lay underneath the middle region of the 

 head. On the head, beside and behind the hypostome, are shown 

 four pairs of appendages; in front of them are the long, jointed 

 antennules. Most students of trilobites today believe that the animal's 

 mouth lay just inside the posterior edge of the hypostome, and that the 

 stomach and other organs were enclosed in the capsule formed by the 

 hypostome and the middle part of the head. The alimentary canal 



