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Volume 78, 1950
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The Type of the Ammonite Madrasites mckayi (Hector)

[Read before the Wellington Branch, October 13, 1949; received by the Editor, October 18, 1949.]

Summary

After being missing for 30 years, the holotype and only known specimen of Madrasites mckayi (Hector) has been recovered, thus ending confusion that had arisen as to its systematic position.

Recently, while unpacking an old case of specimens at the Geological Survey, Mr C. A. Fleming found what can be confidently taken as the original of Alexander McKay's ammonite from Waipawa Gorge, Hawke's Bay, Before the advent of Dr H. J. Finlay's foraminiferal work, the Cretaceous age of the containing beds was not regarded as established, so that the apparent loss of McKay's specimen, and the failure to find any others at Waipawa, caused much doubt about McKay's supposed “find.” The recovery of the specimen not only clears up this systematic question, but, as set forth below, it also resolves some further confusion incidental to the disappearance.

Madrasites mckayi (Hector). Plate 59

  • 1886. Ammonites mckayi Hector, Outline Geol. N.Z. Append. Official Oatal. Ind. and Colon. Exhib., 57, Fig. 19A, No. 4.

  • 1895. Kossmaticcras (Madrasites); Steinmann, New. Jahrb. f. M. G. P., 10, 28.

  • 1910. Kossmaticeras maccoyi; Haug, Traité de Géol., 2, 1345 (lapsus for mokayi).

  • 1921 Kossmaticeras (Madrasites) oumshewausis (Whiteaves) ?; Spath, Ann. Sth. Afr: Mus., 12, (7), 299.

The specimen consists of two pieces, number one, containing more than half of the ammonite, shows the right, side and the umbilical area, number two bears only the external print of the left side of the missing body chamber. The ribs become much coarser with the growth of the outer whorl, not gradually, but in three stages. Those on the inner whorls and the first third of the outer whorl are fine, about 1 per mm. at the periphery, on the middle third they are 3 to 4 per 5 mm., and on the final third they are 2 to 3 mm. apart. Sinuous, broad sulcations cross the whorl, somewhat irregularly disposed, those on the middle third closest (about 20° apart), but only one on the last third. The primaries are raised into weak tubercles margining the widely open umbilicus and one, two and sometimes three interstitials develop distally.

Dimensions. The present measurements do not indicate the original shape because of the extreme compression since burial, also the shell material is completely leached away. The present maximum diameter is about 96 mm., and the thickness about 5 mm.

The bare bones of the synonymy fail to show the interesting history of the single specimen, and it is, therefore, advisable that this be set down.

Picture icon

Madrasites mckayi (Hector). Holotype X 4/3. Waipawa Gorge, Hawke's Bay.

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When unpacked by Mr Fleming, the specimen was accompanied by the following note in the handwriting of Mr Henry Woods, “This ammonite was sent by Dr Allan Thomson, April, 1915, from Isolated Hill Creek—found in the stream gravels. The specimen has been examined by Mr L. J. Spath, who thinks it is likely to be Kossmaticeras (Madrasites) cumshewaensis Whiteaves sp. (Mesozoic Foss., vol. 1, Geol. Surv. of Canada, pl. 24, f. 1). If this is right the horizon is Senonian. This species has been recorded from the Antarctic.”

In his report on Clarence Valley, however, Thomson (1919: 316), under the heading “Isolated Hill Creek, Ure Valley,” wrote, “One large ammonite was obtained in a concretion from the stream-gravels, but was declared by Mr H. Woods to be indeterminable.” The specimen before us comprises two separate pieces that fit together, forming a thin slab (9 ½ in. x 5 ½ in. x ½ in.) of light grey, moderately indurated mudstone with rusty film along bedding planes. It certainly does not look like a concretion from stream gravels. On each of the two pieces is written in faded ink the number 186. Most of the old Geological Survey fossils have the locality number written on a small oblong of paper glued to the specimen, but some odd specimens have the number written, like this one, directly on the matrix.

Number 186 is from. “chalk marls” on the south side of Waipawa Gorge. There, McKay (1879: 73) collected an ammonite which was regarded as one of his early triumphs, because “hitherto, lithological characters alone were depended upon in referring these rocks (Waipawa chalk marls) to the Cretaceous period.” (Hector, 1879: 27.) Indeed, Hector (1886: 57) published a figure of the specimen and named it Ammonites mckayi.

Confirmatory evidence that this is indeed McKay's ammonite is given by examples of foraminifera, especially Nodosaria, that show plainly on the surface of the matrix—McKay specifically mentioned Nodosaria as being plentiful.

It is thus clear that in some way, during its travels to, or in, England, the Waipawa Gorge ammonite became associated with an Isolated Hill Creek label, so that neither Woods nor Spath realized the significance of the obscurely written locality number, 186.

In his account of the Waipawa Series in his “Geology of Fossil Localities near Waipukurau,” Thomson (1926: 349) wrote, “The supposed ammonite which he (McKay) obtained from them was some years ago examined by Mr H. Wood of Cambridge who reported that it was a crushed Nautiloid.” It may be that this observation was based on the real Isolated Hill Creek specimen which, however, cannot now be located.

A noteworthy feature of the synonymy is the consistency of the generic placing. Steinmann's judgment was based solely on Hector's considerably idealized figure; and Spath, handling the actual original, though not aware of it, confirmed the generic and subgeneric position.

If the species is really identical with M. cumshewaensis, then mckayi must give way, as a subjective synonym, to Whiteave's specific name which dates from April, 1884. However, Spath's record reads, “K. (M.) cumshewaensis (? Whiteaves) Kilian and Reboul,” thus favouring specific agreement with Kilian and Reboul's Grahamland

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specimens, but questioning actual identity with the Queen Charlotte Island species.

Dr P. Marshall (1926: 167. Pl. 41, F. 4) has figured a Whangaroa specimen with the caption, “Madrasites cumshewaensis? Whiteaves.” In the text, on the other hand, he merely stated that the fragment “in some respects resembles” this species, and he did not include it in his faunal list. At the same time he noted (1926: 197) Spath's tentative record.

Because, with the material available, and in the light of modern concepts on geographical distribution, it would be rash to submerge mckayi as being certainly synonymous with cumshewaensis, the best course is to recognize the combination Madrasites mckayi (Hector) as the correct name for McKay's (almost notorious) Waipawa ammonite.

References

Hector, J., 1879. Progress Reports. Rep. Geol. Explor. during 1878–79, no. 12.

Mckay, A., 1879. Notes on the Geology of the District between Waipukurau and Napier. Rep. Geol. Explor. during 178–79, no. 12.

Thomson, J. A., 1919. The Geology of the Middle Clarence and Ure Valleys, East Marlborough, N.Z. Trans. N.Z. Inst., vol. 51.

— 1926. Geology of Fossil Localities near Waipukurau, Hawke's Bay. Trans. N.Z. Inst., vol. 56.