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Volume 79, 1951
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Genus Beaumontites Browne nov.

Type species: Beaumontites fraseri Browne n.sp.

Shell involute, whorls almost orbicular in early stages, gradually increasing in height, venter always rounded, when narrowed never actually keeled; the sides more or less convex, gently merging into the ventral and umbilical areas. Umbilicus extremely small to closed, wall steep. Surface of shell smooth. Suture line ceratitic, a small triangular bifid ventral saddle separates the wide ventral lobes, the two lateral and four auxiliary saddles are all entire, with lightly narrowed stems, decreasing gradually and regularly across the whorl.

The name is derived from Beaumont Stream, along which the ammonites occur in four separate localities in two miles.

Beaumontites fraseri Browne n.sp. Plate 102, figs. 1, 2, 7, 8, 12

Ventral area narrowly rounded in adult, laterally always gently convex until merging suddenly into the umbilical wall. Saddle bases toothed. The second and third earliest whorls, of seven exposed in vertical section, at a diameter of 1·5 mm., show a simple goniatitic suture line similar to Triainoceras (Eastman's Zittel, 1913: 633, fig. 1185). There is no saddle in the shallow ventral lobe. As far as can be observed, this is followed by two simple, wide, and shallow lobes and two rounded simple saddles. The first whorl seen, as is to be expected, is globose and the succeeding whorls show broadly rounded ventral regions. The body whorl alone shows a narrowed venter which, however, is still rounded and there is no sign of a keel at any stage. The lateral area is always gently convex, gradually merging into the rounded ventral and umbilical regions. The umbilicus is always extremely shallow. In only one specimen among thirty examined at various stages is there a definite furrow behind the aperture; otherwise the surface is smooth.

Sutures: Following the embryonic and the goniatitic stage referred to above, at a surprisingly early stage of adolescent development (as early as 3 mm. diam.) all lobes are ceratitic; a small bifid saddle separ-

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Figs. 1, 2—Beaumontites fraseri Browne n.sp. Paratype × 1.
Figs. 3, 4—Beaumontites bartrumi Browne n.sp. Paratype × 1.
Figs. 5, 6—Beaumontites routi Browne n.sp. Paratype × 1.
Figs. 7, 8—Beaumontites fraseri Browne n.sp. Holotype × 1.
Figs. 9, 15—Beaumontites routi Browne n.sp. Holotype × 1.
Figs. 10, 11—Beaumontites bartrumi Browne n.sp. Holotype × 1.
Fig. 12—Beaumontites fraseri, suture of Fig. 1, × 2.
Fig. 13—Beaumontites routi, suture of holotype, × 2.
Fig. 14—Beaumontites tepungai Browne n.sp. Holotype × 1.

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Fig. 1—Ussuria cultrata Browne n.sp. Holotype × 1.
Figs. 2, 5—Ussuria sp. × 1.
Fig. 3—Leiophyllites marshalli Browne n.sp. Suture of holotype × 2.
Fig. 4—Leiophyllites marshalli. × 1.
Figs. 6, 7—Ussuria cultrata. Paratype × 1.
Fig. 8—Leiophyllites marshalli Browne n.sp. Holotype × 1.

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ates the two portions of the wide shallow ventral lobe, each ceratitic, with at least two denticulations. The first lateral lobe is wide and deep, the base having two denticulations and three strong points. The second lateral lobe is narrower and shorter, and, like all the auxiliaries seen, usually is strongly ceratitic. The first lateral and all succeeding saddles are rounded brachyphyllic anteriorly, the narrowed shanks are all finely toothed. The anterior portions of the sutures take a straight course across the flanks until the umbilical wall is reached, the auxiliaries gradually decreasing in size.

The umbilical walls are steep, as is plainly seen in the earlier septate stages. The body chamber occupies 1 ⅓ whorls.

Holotype in collection of New Zealand Geological Survey (J. Fraser coll.).

Localities: G.S. 5199 (type), 3593, 3592, 3199, Beaumont, Southland.

Diameter, 31 mm. Height of last whorl, 15 mm. Width, 13 mm. Umbilicus, 6 mm.

This species is the commonest ammonoid at Beaumont, occurring at all the localities examined. Although often badly weathered internally, it is particularly plentiful in the tuff deposits at localities 3592, 3593, and 5199, the most northerly deposits so far collected from.

The species is named in honour of my friend Mr. J. Fraser, who collected the holotype in addition to many other specimens. To Mrs. Fraser and to him the writer is indebted for generous hospitality.

Beaumontites bartrumi Browne n.sp. Plate 102, figs. 3, 4, 10, 11

Umbilical and lower lateral area more or less depressed; umbilicus covered or minute. Venter more broadly rounded in outer and penultimate whorls. Saddles smooth.

This species differs from B. fraseri in the more or less depressed umbilical region, as against the gentle but nevertheless noticeable convexity of that region in B. fraseri.

Again the venter is more rounded at maturity. This is less noticeable in the earlier stages of growth. It is the less inflated inner whorls that give the depressed umbilical region, the sections being ovoid instead of rounded. The sutures are similar to those of B. fraseri in having all lobes ceratitic, and all saddles rounded brachyphyllic anteriorly. The points and indentations at the bases of the lobes are not so strongly developed as in B. fraseri. Both cast and shell are smooth in all specimens examined.

The umbilicus is minute or covered.

Holotype in collection of New Zealand Geological Survey.

Diameter, 30 mm. Height of last whorl, 12 mm. Width, 11 mm. Umbilicus, 8 mm.

Locality: G.S. 5199, tuffs with concretions, North Branch, Beaumont Stream.

Beaumontites routi Browne n.sp. Plate 102, figs. 5, 6, 9, 13, 15

Smooth, discoidal, more or less evolute or egredient; gently convex from the shallow umbilicus to the narrow but distinctly rounded venter.

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Adult umbilical area gently concave, more so than in bartrumi. Early whorls involute, globular, gradual increase in relative height and narrowing of venter with growth. No true or fully developed ribs present at any stage and no true constrictions, but incipient radial to posteriorly convex rib-like markings are numerous on the body chamber, but not on the septate portion visible. Body chamber occupies at least 1¼ whorls.

Septa: A flask-shaped siphonal saddle shortly bifid anteriorly (i.e., with a minor siphonal lobelet) dividing a deep and very strongly denticulate siphonal lobe, apically fully as far as the first lateral lobe, and strongly trident. The first and second laterals are similarly strongly trident as is the first auxiliary. Succeeding auxiliaries are ceratitic. At least six and possibly seven lobes excluding the siphonal. Saddles all smooth and rounded anteriorly.

Holotype in collection of New Zealand Geological Survey.

Holotype Paratypes
Diameter 58 mm. (estimated) 43 mm. 30.5 mm.
Height of last whorl 22 mm. 20 mm. 11 mm.
Width 13 mm. 12 mm. 9 mm.
Umbilicus 15 mm. 10 mm. 9 mm.

Locality: G.S. 5199, tuffs with concretions, North Branch, Beaumont Stream.

Beaumontites tepungai Browne n.sp. Plate 102, fig. 14

Slightly evolute, discoidal, outer whorl much compressed, inner ones somewhat inflated. Whorls deeply embracing and very deeply indented by the preceding whorl; greatest width at about ⅓ of height, very gently convex until nearing the venter, which is very narrowly rounded in the body whorl. Septa ceratitic at least 6 lobes and saddles, septa crowded. Body whorl at least 1 ⅓ volutions. Ornamentation variable, never strong, of shallowly sigmoid growth striae and low folds rather irregularly developed, scarcely observable before the last half whorl.

Holotype: New Zealand Geological Survey (R.A.S.B. coll.).

Holotype Paratype (1) Paratype (2)
Diameter 39 mm. 42 mm. 37 mm.
Height 15 mm. 25 mm. 22 mm.
Width — 5 mm. —
Umbilicus 10 mm. — —

Locality: Beaumont No. 1, G.S. 3199, indurated mudstone, cliff at entrance gate to Beaumont Homestead.

This is easily the most common form at Beaumont No. 1. A very large number of fragments were found here and further search will undoubtedly disclose many more.

The species is named in honour of Mr. Martin T. Te Punga, who first located Ammonoids in the Beaumont beds.

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