390 On the Genus Tellinomya^ and allied Genera, 



species like individuals may have Lad the cause of their death 

 inherent in their original constitution, independently of changes 

 in the external world, and that the term of their existence, or the 

 period of exhaustion of the prolific force, may have been ordained 

 from the commencement of each species. 



ARTICLE LV. — On the Genus Tellinomya, and allied Genera^ 

 with Illustrations, by Professor James Hall, Palaeontologist 

 to the State of ISTew York ; written for the Canadian 

 Naturalist and Geologist. 



In the investigations of Palieozoic fossils, it often happens that 

 the most important parts for the determination of the generic 

 characters are obscured or entirely hidden by the adhering stony 

 matter. This is particularly true of the Gasteropoda and Lamelli 

 branchiata, and the generic characters are often necessarily derived 

 from the external features of the shell. It is not always possible 

 to make these determinations with such accuracy, that further 

 discoveries will not show the necessity of some modification. 

 Were the descriptions of the genera and species of the Lamelli 

 branchiate, shells of the Palteozoic rocks, left until the hinge and 

 teeth, the pallial and muscular impressions, could be determined, 

 comparatively few would be described. 



In the first volume of the Palaeontology of New York several 

 new genera were proposed, and among them the genus Tellinomya, 

 which is the subject of the present notice. This genus was con- 

 stituted to include several species, supposed to be related to each 

 other from external characters. These characters were suggestive 

 of Tellina and of Mya, and the name adopted accordingly. 



In the specimens known to me at that time there were no visi- 

 ble teeth or crenulations in the hinge line, and this fact was stated 

 in the description. Subsequently I obtained some specimens 

 which suggested other relations than those indicated by the 

 generic name. No opportunity has occurred of correcting the 

 original description, while in the meantime the species have been 

 referred by Palaeontologists to other genera, and in some instances 

 to those of very different character.* 



* M. d'Orbigny refers tbe species of TeUinomya described in the first 

 volume of the PalaBontology of New York to the genus Lyonsia of Turton, 

 a modern shell belonging to a very diflfereut family ; and to add still more 



