610 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. 49. 



The ribs posterior to the seventh in the type-specimen shorten 

 rapidly and at the same time the shaft becomes very slender. 



The first, second, third, and fourth thoracic ribs are connected with 

 the sternum by cartilagmous ribs, as shown in figui-e 19. In life it 

 is quite likely that several more may have been similarly connected. 



The greatest length of the principal ribs are given in the following 



table of measurements : 



Measurements of thoracic ribs. 



mm. 



First rib preserved on the right side 265 



Second rib preserved on the right side 293 



Third rib preserved on the right side 295 



Fourth rib preserved on the right side 280 



Fifth rib preserved on the right side 269 



Last rib of the series on the right side 38 



The mamier in which the thoracic ribs join the sternal ribs is well 

 shown in figure 19. 



Fig. 19.— Fragment of sternal bone and sternal ribs of Thescelosaurus neglectus 

 GiLMORE. Type No. 7757, U.S.N.M. J nat. size, s, Fragment of left sternal 

 bone; S. r., sacral ribs; 13, 14, 15, and 16, ends of thoracic ribs, counting from 



THE SACRUM. 



Sternum. — The presence of a sternum is indicated in the type- 

 specimen by a fragment of the posterior part of the left sternal bone 

 retained in the matrix nearly in its proper position, and articulating 

 with the partially ossified sternal ribs, as shown ui figure 19. 



The remaining portions of the sternum were weathered away 

 before the specimen was discovered, so there is no information as to 

 its shape and extent. 



