“Monia zelandica (J. E. Gray, 1843). Pl. 5, fig. 3.
1843 Anomia zelandica Gray, in Dieffenbach's Travels in N.Z., p. 260.
1873 Placunanomia incisura Hutton, Cat. Tert. Moll. p. 34.
1914 Placunanomia incisura Hutton; Suter, N.Z. geol. Surv. paleont. Bull. 2: 34, p1.6, fig. 2.
HOLOTYPE (TM 2852) of Monia incisura (Hutton), a complete individual.
TYPE LOCALITY (of M. incisura): "Pareora Beds, Rangitata." The exact locality is unknown. Hutton's specimen was probably collected by Haast during his survey of Canterbury in 1861. Haast (1879, p. 322) recorded "Placunanomia sp." in his list of fossils from the Pareora Formation at Rangitata; he also recorded Placunanomia incisura Hutton from the Oamaru Formation at Rangitata (p. 312).
The type of Monia zelandica (Gray) is a Recent shell described from New Zealand.
ORIGINAL DESCRIPTION (of M. incisura). "Sub-orbicular, compressed, waved, with concentric imbricating scaly laminae; byssal notch very small, anterior; muscular impressions( ?)."
REDESCRIPTION (of M. incisura, based on the holotype): Shell moderate in size, thin-walled, sub-circular, subequilateral, valves closely adpressed, irregularly undulating. Sculpture of fine, scaly, sinuous, radiating threads, about 1-2 mm apart, which increase in number by intercalation towards the distal margin. Interior not seen.
DIMENSIONS: Holotype of M. incisura – height, 48 mm; length, 50 mm.
REMARKS: The holotype of M. incisura is a complete individual with closed valves, and no topotypes are known, but well preserved separate valves of the same species collected from Tengawai River (GS 5177) and Target Gully exhibit in the left valve the two muscle-scars characteristic of Monia. Monia is recorded in New Zealand from the Whaingaroan (Lower Oligocene) to Recent.
No systematic differences have been observed between the mid-Tertiary M. incisura (Hutton) and the Recent M. zelandica (Gray). Shape and disposition of the shell of Monia are much influenced by the environment; strength and spacing of the radial sculpture also appears to be variable. The holotype of M. incisura can be matched with specimens of the Recent M. zelandica.”
(Boreham, 1965: 46)
Monia zelandica, is a species of marine bivalve mollusc in the family Anomiidae, the jingle shells.
