lis I'HOCIOKDINGS OF TRK MALACOLOGICAL SOCIETY. 



ON THE VALUE OF ANCYLASTRUM. 



By Chakles Hedley, of the Australian Museum, Sydney, N.S.W., 



Australia. 



Read March 9th, 1894. 



Aiicylastrum was first defined by Bourguig:nat, Journ. de Conch, 

 vol. iv. p. 63 (contained in a part dated 15th Feb. 1853), and on 

 p. 170 he distinctly names his Ancyhis Cumingianus as the type 

 thereof. This remark he is careful to repeat in his description of 

 that species, Proc. Zool. Soc. 1853, p. 91 (published July 25th, 1854). 



Fischer, in his Manuel, p. 504, credits Ancylastrum to Moquin 

 Tandon, in which he is copied by Tryon, Struct, and Syst. 

 Conchology, iii. p. 107. No hint that Moquin Tandon originated 

 the term is conveyed in Bourguignat's description, but the former 

 writer claims the name as his own in the definition of Ancylastrum in 

 his work on the Land and Fluviatile MoUusca of France, ii. p. 483. 



Another reference to the classification of this form is a note 

 by Hanley, communicated by Legrand to the Proc. Roy. Soc. 

 Tasmania, 1871 (1872), p. 27. He says: "One of your fresh- 

 water species is quite a novelty ; it is even of generic importance. 

 It is almost a Gundlachia, but merits distinction. I propose for it the 

 name Legrandia, in honour of the discoverer." 



Clessin, in his monograph of the Ancylinm in the " Conchylien 

 Cabinet," chooses to consider Ancylus Jiuviatilis as the type of 

 Bourguignat's Ancylastrum, for the actual type of which he proposes a 

 new group. To complete this literary ruin he selects Cumingia as 

 the name for his new group, a name preoccupied in the Mollusca by 

 Sowerby, P.Z.S. 1833, p. 34. 



To conclude, modern authors have persistently assigned to 

 Ancylastrum a value it does not possess. Since the describer of 

 the group clearly and repeatedly declared his type to be Cumingianus 

 it is not legitimate for Fischer, Clessin, or Tryon to alter the type of 

 Ancylastrum from A. Cumingianus to A. Jiuviatilis. That Bourguignat 

 also included A. Jiuviatilis and other members of Ancylus proper in 

 Ancylastrum is unfortunate, but it does not invalidate the genus. 

 It is probable that ISloquin Tandon privately suggested the word 

 Ancylastrum to Bourguignat, but as a published name we have 

 no choice but to cite Bourguignat as the author. 



The shell characters of the monotypic Ancylastrum appear to me to 

 differentiate it from Ancylus, to associate it rather with Latia and 

 Gundlachia, and to entitle it to rank as an independent genus. 



