342 



•appendages called deltidia, which are in some species united together 

 in the middle, in which case the perforation is rendered entire j 

 when they are separated it is incomplete : these deltidia are of an 

 elongated form and continue from the anterior margin of the 

 cardinal area to the apex in those species (T. psittacea and 

 T. nigricans) that have a pointed beak. It is also to be remarked 

 that these species are not punctated on the surface as all other 

 species are. 



Terelratula was formerly placed among his Anomice, by Linne ; 

 it is however very easily distinguished from the legitimate Anomice, 

 by its regularity, its produced beak, its being attached by a fibrous 

 peduncle and by its internal appendage. The recent species of 

 the genus are found in all climates, and they are for the most part 

 very abundant in all localities where they occur. 



We have never been able to meet with T. rotundata of Lam. 

 represented in Encycl. meth. t. 239. f. 5. 



DESCEIPTIONS. 



Inqmnctatce. 



1. Terebratula psittacea (pi. lxxi. f. 78, 79, 80.) Lam. 



Testa subglobosa, postice acuminata, tenui, nigricante, valvis 

 insequalibus, radiatim concinne striatis, linea, marginali ex umbones 

 declivi, clemum ascendente et antice valde sinuata ; valva, dorsali 

 postice acuta, recurva, antice deflexa, sulco mediano lato, indistincto, 

 foramine trigonali, haud integro ; area cardinali inconspicua, ro- 

 tundata, deltidiis angustis, ad lateres foraminis coalescentibus ; 

 valva ventrali ventricosa, antice latiori, carina mediana inconspicua, 

 ad margin em anticum solummodo distincta ; dentibus cardinalibus 

 intends ex umbonem porrectis recurvis duobus ad utrumque latus 

 uno : margine valvarum integerrimo. 



Trom Labrador, where it is found in abundance in the mud on 

 the shore at low water : dredged alive at Melville Island by Lieut. 

 Griffith. 



2. Teuebeatula nigricans (pi. lxxi. f. 81, 82.) nobis. 



Testa antice rotundata, postice acuminata, tenuiuscula, nigricante, 

 valvis insequalibus, radiatim costatis, costis rotundatis, linea margi- 

 nali rectiuscula, ; valva dorsali subtrigona, depressiuscula ; antice 

 rotundata, lateribus posticis declivibus, foramine magno, haud 

 integro, quadrato ; area cardinali magna, planiuscula, lateribus 



