PLATE III. 



Terebratula flavescens. 



Fig. 



1. The visceral mass and portions of the mantle-lobes, dissected to show the hearts and 



principal venous sinuses. Magnified 8 diameters. 



2. The soft parts, as seen from the dorsal aspect, and exposed by the removal of the 



dorso-pallial fold and spiral extremity of the arms. Magnified 6 diameters. 



3. A similar view of the soft parts, with a minor degree of dissection. 



The following are the letters or marks of reference used for the same parts in each of 

 the figures. 



D Dorsal, or imperforate valve. 

 a Cardinal process. 

 b Dental sockets. 

 c Cardinal plate. 

 d Median crest. 



e Crus, or basal process, of loop. 

 e' Descending process of loop. 

 / Produced plate of loop. 

 ^ Reflected plate of loop. 

 h Transverse, or confluent plate, of loop. 



IMPRESSIONS OF 



o' Adductor longus anticus. 

 y ,, ,, posticus. 



q Adductor brevis. 



V Ventral, or perforate valve. 

 i Foramen. 

 k Deltidium. 

 / Cardinal teeth. 



3 c 



