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Volume 57, 1927
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Part 1. Introduction.

Perhaps in no other family of the Mollusca is it so difficult to reconcile the classifications and nomenclatural systems of different authors as in the Veneridae. This is a stumbling block to New Zealand conchologists who, owing to the lack of extensive foreign collections and of a large proportion of the older literature, have to depend on quotations, often without figures, for much of their information. As to the generic grouping of species, no great difficulty is presented by the shells of this country, so that if one could start with a set of new generic names the task would be a light one. This procedure, however, would conceal the resemblances which our Veneridae show to those of other countries, and valuable information as to faunal origins and migrations might be overlooked. Therefore in the following classification an attempt has been made to preserve such external relationships as are considered close, without making any undue sacrifice of accuracy.

In the diagram given by Suter (1913, p. 827) to illustrate the parts of a Venerid shell, the posterior cardinal tooth has, by a slip, been labelled “posterior lateral,” also several characters commonly

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Picture icon

Fig. 1.—Diagram of the left valve of Kuia vellicata (Hutton) × 3.

used in descriptions are not indicated. Consequently the following revised diagram is given.

  • A, anterior margin

  • B, posterior margin

  • C, dorsal margin

  • D, ventral margin

  • A-B, length

  • C-D, height

  • 1, posterior cardinal tooth

  • 2, median cardinal tooth

  • 3, anterior cardinal tooth

  • 4, anterior lateral tooth

  • 5, nymph

  • 6, resiliary surface of nymph

  • 7, ligamental groove

  • 8, escutcheon

  • 9, lunule

  • 10, pedal retractor scar, out of sight under the hinge plate.

  • 11, anterior adductor scar

  • 12, posterior adductor scar

  • 13, pallial line

  • 14, pallial sinus

  • 15, marginal crenulations

  • 16, umbo

The chief modern students of the Veneridae have been Dall (1903), Jukes-Browne (1908-1914) and Cossmann and Peyrot (1911). These writers disagree greatly not only in the relative evaluation of shell characters, but also in the application of the Rules of Nomenclature. Dall has consistenty advocated a strict observance of the International Rules, and always supplies references to the literature, therefore he is the most reliable guide.

Suter, in his Manual (1913) followed Dall's classification almost completely, and although several necessary changes were pointed out by Jukes-Browne and Iredale, he did not accept them in his subsequent works on the Tertiary Mollusca (1914-1921).

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In the primary division of the family into subfamilies the tendency seems to have been to err on the side of conservatism. Deshayes (1853) recognised four subdivisions, Dosiniana, Meretriciana, Venusiana and Tapesina. Fischer (1887) favoured only three, merging the Dosiniinae with the Meretricinae. Dall again separated the Dosiniinae, but united the Tapetinae with the Venerinae and recognised a further subfamily, the Gemminae (with which we in New Zealand are not directly concerned). Jukes-Browne argued that the Dosiniinae were no further removed from the Meretricinae than the Tapetinae were from the Venerinae, and so recognised only two subfamilies Meretricinae and Venerinae. This tendency to restrict the number of subfamilies probably arose from the difficulty of drawing sharp boundaries, defined in a few words, between the proposed divisions. There has also been some divergence in the principles governing these systematic classifications.

The writer is inclined to think that the division of the Veneridae into at least seven or eight subfamilies would agree better with the relationships displayed, but this subject requires a great deal more research before conclusive opinions can be formed. In the present paper the Dosiniinae are kept apart from the Meretricinae and the Tapetinae from the Venerinae. There may be difficulties in defining these groups concisely, but the guiding principle should be relationship, not ease of definition.

Acknowledgments.—To all those who so kindly supplied information and who lent or gave Venerid specimens the writer is deeply indebted.

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