ZOOLOGICAL AND BOTANICAL ASSOCIATION. 259 



placed in a new sub-genus of Terebratula." On reading this remark, 

 I wrote to Mr. Jeffreys, who, in return, kindly forwarded to me all his spe- 

 cimens, so that I might be enabled to form some opinion on the question 

 he had raised. The principal generic character of Gwynia is in the labial 

 appendages being attached directly to the shell (first observed by Mr. 

 Jeffreys), and not to a loop, as in other genera of the same family. 

 The prominency of the umbone of the small or receiving valve, the form, 

 position, and (considering the size of the species) unusual development 

 of its teeth, also the large size of the perforations of its shell tissue, 

 form other good distinguishing characters. In being sub-auriculated 

 it resembles Terebratulina. The absence of a loop seems to oppose the 

 genus being placed in the family Terebratulidae ; but I prefer retaining 

 it thus, until other differences are made out : possibly when the animal 

 is known, more satisfactory data on this point may be discovered. 



Gwynia capsula. 



1, outer surface of the large valve. 



2, outer surface of the small valve. The projecting portion is the pedicle. 



3, inside of large valve, showing teeth and deltidial fissure. 



4, inside of small valve, showing dental sockets. 



5, longitudinal section of both valves, in the closed state. 



Family.— WALDHEIMID^) {King). 

 Diagnosis. — Receiving valve generally furnished with a long, deeply 

 recurved loop, having its crura attached, one to each of the dental protu- 

 berances, and occasionally, its anterior portion united to the centre of 

 the valve by one or two connecting processes : loop supporting the labial 

 appendages throughout their entire extent. Pedicle muscles often 



