On a Cane of Secondary Adaptation in a Tortoise, l^t!"* 



food ran tlic risk of being: spilt or spoilt if no cloan hole was 

 cut tlirou;ili the leathery covering docs not seem liazjirdona. 

 It is evident that promnxillary teeth never woulil be capable 

 of cutting a neat hole iu a leatherj bag containing semifluid 

 material. 



(4) Tliat the swallowing of some semifluid material was 

 likely to be accompanied by a rapid fore-and-aft movement 

 of the head is not at all surprising. As Osborn pointed nuf, 

 the existence of such movements in Sfruthiomimug is ren'lered 

 probable, by the structure of the cervical vertebraj. 



(5) Since remains of Sti'ulliiomiimts occur frequently in 

 seashore deposits, we can assume that it was frequently to be 

 mot with on sandy beaches, where it couM rash along on the 

 sand and avoid muddy regions. 



Summing up, we may assume that Slnit/iiomimus frequently 

 found its food in the pand along the shore, uncovered it with 

 its hind legs, lilted it with its hands, opened the leathery 

 covering with the beak, and swallowed the semifluid conteiits, 

 jerking its head while swallowing. So Strnthiomimns seems 

 to have been an egg-devouring Dinosaur of the very worst 

 sort, frequently pursued by the animals whose nests he 

 robbed. 



That reptile eggs were abundant during all the Mesozoic 

 j>eriod, and that they were also then especially abundant on 

 dry and sandy beaches, is beyond doubt. As to the appa- 

 rently curit'US feature of a carnivorous Dinosaur becoming 

 adapted to the eating of eggs, tiiis is paralleled in the Varanidai 

 and the snake Dast/peltis. 



To convey to the general reader an idea of how Struthio- 

 mt'vnis probalily behaved when robbing a nest, a reconstruction 

 is given herewith (p. 153). 



London, March 1922. 



X\ J. — ^1 Case of Secondary Adaptation in a J ortoise. By 

 Baron FRANCIS NOPCSA, Foreign Corresp. Geol. Soc. 

 London. 



In all tortoises possessing a well-developed jilastron and no 

 large raesoplastron, the middle elements — viz., hyoplastron 

 and hypoplastron — are always at least as long as each of the 

 terminal elements — viz., epiplastron (entoplastron) and 

 xiphiplastron. Exceptions are only to bo found in the 

 Chclydidie and Cinostornidee. Sometimes, especially iu 



