TRANSACTIONS OF WAGNER 

 IOO6 



TERTIARY FAUNA OF FLORIDA 



portance. A favorite basis has been the coalescence of the siphonal retractor 

 scars with the basal part of the pallial impression. Such characters, con- 

 venient for sections when constant, in a genus containing numerous species, 

 should not be taken too seriously; as the moving of the ventral part of the 

 retractile apparatus a fraction of an inch with respect to the points of attach- 

 ment of the pallial margins is surely not of much weight. A matter which 

 has greatly added to the difficulty of clearing up the synonymy is the reckless 

 manner in which authors who in other respects have done excellent work 

 have disregarded all rules of nomenclature and have altered, consolidated, 

 and proposed new names with apparently no consideration of the mischief 

 they were doing or the difficulties created for other workers by such conduct. 



The hinge of Tellina in the broad sense, when developed to the fullest ex- 

 tent, comprises on each valve an anterior and posterior lateral and two cardinals, 

 of which one is grooved or bifid on its distal edge. When the valves are closed 

 the two bifid teeth are central and the simple teeth are respectively anterior 

 and posterior to them. Normally the teeth of the right valve close in in 

 advance of the teeth of the left valve, and in the obsolescence of the laterals 

 those of the left valve disappear first. The simple cardinal of the left valve 

 is often very close to and hardly distinguishable from the anterior ^part of 

 the nymphal callosity, and, owing to its fragility, is often broken off at the 

 base, leaving hardly a trace, from which circumstances proceed the erroneous 

 diagnoses so common in the literature which ascribe a single left cardinal to 

 sundry species or groups of Tellinas. No Tellina is without two cardinal 

 teeth in each valve and at least one (anterior) lateral tooth in the right valve, 

 unless it has been deprived of these parts by erosion, fracture, senility, or ab- 

 normal growth. 



It occasionally happens that the hinge of an individual will be reversed 

 with respect to the valves of normal specimens, but I have found' no species 

 in which the hinge is habitually reversed. The laterals are stated by Bernard 

 to appear independently of and later than the cardinals, and in those species 

 where the laterals are distant from the cardinals they do not develop from 

 the shank of a x-shaped nepionic tooth, as do the laterals of many Teleodont 

 bivalves. I am inclined to believe, however, that the so-called " adjacent" 

 laterals may arise in the above-mentioned manner, as they often appear to 

 retain some connection with the anterior cardinal, and, in fact, have been 

 described by several authors as cardinals. In the subgenus Omala the adjacent 

 lateral is so close to the cardinals and so like them that it is not surprising 

 that it has been taken to belong to the cardinal series. 



