EARLY DEVOXIC HISTORY OF NEW YORK AND EASTERN NORTH AMERICA 



165 



a mode of treatment which I have frequently used with success in elucidat- 

 ing the structure of calcareous fossils in a calcareous matrix it has been 

 possible to produce the accompanying drawings of the internal cast of the 

 calyx and the nearly complete exterior surface of the cup with the immense 

 gastropod attached. In a recent discussion of symbiotic conditions among 

 Paleozoic organisms I have given some attention to these singular conso- 

 ciations of gastropods with the Cri- 

 noidea and have illustrated a number 

 of striking instances without attempt- 

 ing- to exhaust the record of them, 1 

 but in all records there is no parallel 

 to this for the extravagant dispropor- 

 tion between the size of the parasite 

 and its host. Indeed it seems very 

 probable that the growing weight of 

 the gastropod (Orthonychia 

 tortuosa Hall, a species before 

 recorded from the fauna) finally so 

 overbore the crinoid as to bring its 

 head to the ground. Thus the para- 1 

 sitic act made the conservation of '••-; 

 this unique specimen possible. 



The crinoid is a Melocrinus of 

 undescribed species. It may be Mel °" in " »■!«» L ' A " se au Sauva f e - 1 The exterior 



1 J of the calyx and the attached gastropod, Orthonychia 



knOWIl aS M. m i CmaC . The figure tortuosum - >-} Opposite sides of the internal cast of the 



o same calyx, showing the dome and the interior sculpture of 



of the exterior shows the short sharp the pla,es - 4 Fragment of the column 

 nodes at the centers of the radial series of plates and the radiating 

 series of six ridges which traverse these and the rest of the calyx plates. 

 Even some of the interradials are sharply nodose. Basals not preserved. 

 Mr Edwin Kirk has examined this specimen and draws my attention to its 



, The Beginnings of Dependent Life. N. Y. State Mus. 4th An. Rep't Director. 1908. 

 p. 146-69, pi. 1-13. 



