3l8 TRANSACTIONS OF THE WAGNER FREE 



carina on each side of the equatorial sulcus which may be simply finely spirally 

 striate or have one or two beaded spiral threads, like those of var. cingtdata, 

 in it. The basal margin is formed by a spiral rib, and there are often two 

 faint ribs between the shoulder of the whorl and the suture. This form 

 reaches a length of 72 mm., and a basal diameter of 12 mm. 



For those who insist on dividing specifically specimens which may be 

 the progeny of a single pair, the above varietal names may take specific rank. 

 For myself, I believe, in the present state of science, that most stress should 

 be laid upon the relationship, rather than trifling points of difference, since, in 

 the dust-cloud of names applied to every individual mutation, all general 

 principles become obscured. 



I may add that the Pliocene Turritella Cooperi Carpenter, which has per- 

 sisted until recent times on the Pacific Coast, and was collected by Orcutt at 

 San Quentin Bay, Lower California, with other Pliocene fossils, has a quite 

 marked general resemblance to T. apicalis, though a ruder and less elegantly 

 sculptured shell. 



Family MATHILDIID^. 

 Genus Tuba Lea. 



Tuba Lea, Contr. Geol., p. 127, 1833. Type T. striata Lea ; Conrad, Am. J. Conch, i. p. 34, 



1865. 

 Mathilda Semper, Journ. de Conchyl. xiii. p. 328, 1865 ; Dall, Rep. Blake Gastr., p. 266, 



1889. 

 Cingidina A. Adams, Ann. Mag. N. H. 1S60, vol. vi. p. 414 ; fide Newton. 

 Gegania Jeffreys, P. Z. S. 18S4, p. 365, pi. xxvii. fig. 10, 18S4 ; R. B. Newton, Brit. Olig. 



Eoc. Moll., p. 209, 1891 ; Dall, Rep. Blake Gastr., p. 268, iSSg! 

 Acroccelum Cossmann, Cat. Eoc. Paris, iii. p. 315, t8S8. 



The forms grouped under this genus have met with various fortune in 

 nomenclature. The type of the genus is a large species (when adult) of the 

 same character as that subsequently described by Jeffreys as Gegania. Cingu- 

 lina A. Adams (not of Monterosato, 1880) is treated by Newton as equivalent 

 to the later Mathilda of Semper. There is nothing in Adams's diagnosis and 

 description of his single type-species (C circinata) to oppose or confirm this 

 statement; in fact, it would be impossible for any one to refer Cingtdiyia to its 

 family from any information furnished by Adams. It is to be supposed that 

 Mr. Newton's information was derived from an examination of Adams's type- 

 specimen in the British Museum collection. It is to be regretted that he has 

 not informed his readers of his reasons for the identification, especially as his 

 course in matters of nomenclature in several cases has been such as to render 

 necessary a thorough investigation of each case before his proposed changes 

 or statements, as of fact, can be safely accepted. The type of Cingidina has 

 not, I believe, been figured. 



Semper, on the other hand, has fully and sufficiently described his genus, 



