236 PROCEEDINGS OP THE MALACOLOGICAL SOCIETY. 



Thirdly, it is absurd to say that V. cequilatera is " more compressed, 

 equilateral, and trigonal " than V. imdulosa. In making such a 

 statement Dr. Dall must again have been thinking of the shells which 

 he considered " more typical than the type." 



Lastly, I cannot see that either V. faha or V. fumigata, which latter 

 is identical with V. Icevigata, Sow., has any close resemblance to 

 V. cequilatera, but both might be classed in the same group as 

 T. pinguis. 



I regret to find myself so much at variance with Dr. Dall both in 

 regard to facts and in regard to the affinities of certain species, but 

 the result of my investigation is a conviction that his description of 

 the Gomphina group must be considerably modified. It is very 

 probable that the effect of the Messrs. Adams' restriction of the name 

 to a single species did not occur to him, or he would doubtless have 

 retained that species as the type. The adoption of V. donaeina as the 

 type will of course nullify the section Macridiscus, and I do not 

 propose to create a new one for V. undulosa, as, in spite of some small 

 differences, 1 do not think there is sufficient reason for splitting 

 Gomphina into two sections. The fact is that in all the species of this 

 group there is great variability in the extent to which the teeth are 

 grooved. In some specimens of donaeina all the teeth but two are more 

 or less grooved, while in imdulosa the number of grooved teeth varies 

 from one to three. 



Finally, though, as above stated, I would exclude T. pinguis and its 

 allies from close association with Gomphina, there is another small 

 group of shells which should in my opinion be ranked as a section or 

 subgenus of Gomphina. This is the group typified by V. Jluctuosa, 

 Gould, which Dr. Dall separated from Tapes in 1870,^ and considered 

 so distinct as to deserve generic rank, giving it the name of Lioeyma. 

 I quite agree that it should be separated from Tapes, but though the 

 external form does not much resemble that of Gomphina, its hinge will 

 be found to agree very closely with that of G. donaeina. 



Dr. Dall describes L. Jluetuosa as having "three cardinals in each 

 valve, the posterior left and anterior right entire, the others bifid or 

 grooved." As my own three specimens of this species did not agree 

 with this statement, having all the teeth entire except the right 

 posterior, and in one specimen a grooved left median, I asked 

 Mr. E. A. Smith if he would examine the specimens to see if any 

 agreed with Dr. Dall's description. This he was kind enough to do, 

 and wrote as follows: "In some specimens (not in all) I find the 

 teeth as described \)j Dr. Dall ; the grooving, however, is shallow and 

 often so feeble as to be difficult of detection ; moreover, it is not 

 constant, for in some instances the posterior of the right and the 

 anterior of the left may be ungrooved." 



Here again, therefore, we find the same curious variability and the 

 same tendency to solidity of the teeth which shows itself in Gomphina ; 

 but as in the latter, so also in Lioeyma, the teeth which are most 



1 Pi'oc. Bost. Soc. Nat. Hist., 1870, vol. xiii, p. 256; and Am. Journ. Conch., 

 1871, vol. vii, p. 145. 



