Art. VII.—Description of a New Species of the Family Cerithiidae.
[Read before the Philosophical Institute of Canterbury, 18th September, 1918; received by Editor, 25th September, 1918; issued separately, 14th May, 1919.]
Fastigiella australis n. sp.
Shell elongate-conical, gradate, many-whorled, with slightly nodulous cinguli; aperture oval-quadrangular; columella with a distinct fold produced by the entering of the carina of the fasciole. Sculpture: The post-embryomic whorls have a prominent convex and faintly nodulous spiral band below the suture; a similar but narrower band above the lower suture, and below it a fine thread margining the suture. The paratype, which is smaller, shows only the upper band and a distinct thread above the suture below. On the lower whorls the thread margining the suture is lost; strong convex and distant growth-lines turn up which are produced into nodules on the upper and lower cinguli, but the specimens before me, no doubt considerably worn, show only traces of these characters. The body-whorl is distinctly angled and bears two cinguli upon the angle. The base of the paratype shows traces of spiral striation. Spire high, distinctly gradate, angle about 20°. Protoconch lost. Whorls 8 on the imperfect holotype, flat or somewhat concave between the cinguli, the body-whorl angled. Suture deep, canaliculate in the paratype. Aperture ovate, but slightly quadrangular, not channelled above; most likely with a very short and notched canal, but the whole of the mouth is too much damaged in both specimens to be quite certain. Outer lip straight, curved and indistinctly angled towards the base. Columella a little excavated above, bearing on its lower part a fold which evidently extends as a carina upon the fasciole, but the latter is almost completely broken off. Inner lip spreading somewhat over the base, more apparent on the paratype.
Height, 22 mm.; diameter, 8 mm. (imperfect holotype).
Holotype and one paratype in the Canterbury Museum, Christchurch.
Loc.—Holotype from the upper horizon, Whitewater Creek, and the paratype from the upper horizon, Struthiolaria bed, Porter River, Trelissick Basin; both collected by Mr. R. Speight, Curator of the Canterbury Museum.
Remarks.—The genotype is Fastigiella carinata Reeve, a living species from the Antilles, and our species differs from it chiefly in the aperture not being channelled above. The umbilicus of the type I take to be simply
a deep impression inside the fasciole; Cossmann does not mention an umbilicus in the diagnosis of the genus. Besides the Recent genotype, about half a dozen Tertiary species are known, the genus being evidently of rare occurrence. F. australis is, as far as I know, the first species recorded from the Southern Hemisphere.
The Cerithiidae are but scantily represented in the New Zealand Tertiary. At the present time the following six species are on record: Cerithium hectori Harris, Besanconia huttoni (Cossm.), Fastigiella australis Sut., Cerithidea bicarinata (Gray), C. tricarinata Hutt., and Batillaria pomahakensis Harris.