NATURAL SCIENCES OF PHILADELPHIA. 453 



Monograph of the Family TEBEDID.E. 

 BY GEORGE W. TRYON, JR. 



The following is the third and concluding paper of a series,* designed to 

 comprehend all that is at present known, regarding the curious group of shells 

 included in Blainville's Order Pholadacea: 



In the preparation of these papers much difficulty has arisen from the num- 

 ber of species which have been described (sometimes inadequately) but not 

 figured, and from the conflicting views of European naturalists regarding the 

 validity of many species. There is no good reason why the Pholadaceae should 

 i not be searched for, and distributed very generally in public and private cabi- 

 nets, yet such is not the case, and every conchologist who studies the order 

 labors under the disadvantage of being unable to examine and compare speci- 

 mens, of a large number of the species. Greatly as the number of species have 

 been increased by modern research, it is evident, from the general diffusion of 

 the order throughout the world, and from the incompleteness of our researches 

 in those regions, which appear most to abound in them, and also from the 

 number of new species in one of the families discovered recently in England 

 alone, that the number at present known must be indeed a very small propor- 

 tion of those which future investigations will probably reveal to us. 



If these pages shall direct attention to the collection and study of the Phola- 

 dacece, and furnish an approximate idea of the amount of the previous labors 

 of conchologists, they will have answered their purpose. Should material be 

 placed at my disposal for a more perfect study of these shells, a complete illus- 

 trated monograph will be published at some future time. To further this end, 

 collectors are earnestly requested to send to me (in exchange), specimens from 

 all duly authenticated localities, together with such facts in relation to them as 

 may come to their knowledge, and such assistance will be fitly acknowledged 

 in the proposed publication. 



Sellius was the first naturalist who studied the species of Teredo, and his 

 work on their natural history is a model of accuracy in most particulars, going 

 far in advance of all other treatises on the subject which appeared for many 

 years afterwards. 



So little did Linnaeus and his immediate followers know of the species of 

 Teredo, that they included a number of species under the name of T. navalis, 

 which is published with such a general description as will suit all the species 

 now known, or hereafter to be added to the genus 1 Lamarck did not add much 

 to our knowledge of these shells, and Dr. Gray has merely given us at two 

 widely-extended periods, lists of the species, one or two descriptions, and some 

 interesting and important investigations regarding the shell of Kuphus arenarius. 

 Conchology is deeply indebted to the following naturalists for a large portion 

 of our knowledge of the family : Blainville, who published a number of new 

 species in the "Diet, des Sciences Naturelles." Deshayes, who has given us 

 extended anatomical descriptions in the Mollusca of the Scientific Exploration 

 of Algiers. Fischer, a Monograph of the family in " Journ. Couch.. 2 ser., 

 vol. i." Turton, for several new species. And more especially to Mr. Gwyn 

 Jeffreys for his accurate diagnoses of new British species, and to Mr. Hanley 

 for the splendid descriptions which he has published in the " History of British 

 Mollusca." 



I have endeavored, as far as possible, in the present paper to separate the 

 species by distinctive characters, but their value is seriously impaired in this 

 family by the fact that, unlike the Pholadidae, the specific distinctions are not 



* " Synopsis of the Recent Species of Gastrochaenidae, a Family of Acephalous Mollusca." Proc. 

 Acad. Nat. Sc, Dec, 1861. 



"On the Classification and Synonymy of the Recent Species of Pboladida?." Proc. Acad. Nat. 

 Sc, April, 1862. 



1862.] 



