4. Fauna of the Titirangi Series.

a. General Discussion.

The lower twelve feet or so of Titirangi Bluff is formed of fairly soft Bryozoan limestone, on the eroded surface of which lie the Titirangi beds. No angular unconformity can be observed between the limestone and the shell beds; both are practically horizontal.

The fossils are in a beautiful state of preservation, and can be obtained in countless numbers, the one drawback being that the variety of species is comparatively small. Thirty-eight species were obtained of which twenty-six are Pelecypods and twelve Gasteropods. This predominance of Pelccypods, their large size and strength, and the great numbers of Amphidesma, indicate that the containing beds were laid down in quite shallow water bordering an open beach of shell sand.

Sixteen of the thirty-eight are Recent species, that is 42%. This suggests correlation with the Waitotaran or lower stage of the Wanganuian system, although the most characteristic species of that stage are not represented. The large heavy Eumarcia which is common in the basal four feet of the shell-bed at the western end of the outcrop appears to be conspecific with E. plana Marwick from the Waitotaran and the lower part of the Nukumaruan beds. Also Paphirus largillierti (Philippi), Gari stangeri (Gray), Zemysia zelandica (Gray), and Glycymeris modesta (Angas) are present in great numbers, and Dosinia wanganuiensis Marwick is not uncommon. The writer therefore favours correlation with the Nukumaruan, i.e., the middle stage of the Wanganuian. The European equivalent of the Titirangi beds is thus about Middle Pliocene.

Specimens of a large barnacle from the Titirangi beds were submitted to Mr. T. H. Withers of the British Museum. He identified them as Balanus (Megabalanus) tubulatus Withers (1924, p. 28, pl. 7, figs. 1–10). This species was originally described from the Lower Pliocene of Castle Point and Waipara Gorge, New Zealand.

b. List of Fauna from Titirangi.

(Recent species marked *)

• Barbatia (Acar) whangaensis n. sp.

• *Glycymeris laticostata (Q. and G.)

• Glycymeris waipipiensis Marwick

• *Glycymeris modesta (Angas), common.

• Philobrya galerita n. sp.

• Perrierina ovata n. sp., common.

• *Mytilus (Aulacomya) maorianus Iredale.

• Chlamys titirangiensis n. sp.

• *Limatula maoria Finlay.

• Neogaimardia elegantula n. sp.

• Cuna firma n. sp.

• Venericardia martini n. sp., common.

• Condylocardia torquata n. sp.

• *Zemysia zelandica (Gray), common.

• *Myllitella pinguis n. sp., common.

• Amphidesma (Taria) porrectum n. sp., common.

• *Mactra rudis Hutton.

• *Scalpomactra scalpellum (Reeve).

• Dosinia (Phacosoma) wanganuiensis Marwick.