Stromboidea
Original Description of Perissoptera elegans by Kase & Maeda, 1980:
- "Medium or small siyed and thick shelled aporrhaid with highly turriculate spire attaining less than a third of total shell height. Incremental angle in neighbourhood of later whorls about 35, while apical angle about 55. Spire whorls ten in number including protoconch, regularly expanded in size, roundly convex, and separated from each other by impressed suture. Protoconch small, rounded, smooth, naticiform, consisting of about four whorls, gradually changing into ornate teleoconch without a distinct boundarz. Sculpture of spire whorls consistentlz composed of 13 in number on penultimate whorl, and their inclination against shell axis gradually becomes stronger through growth. Spiral cords fine and numerous (about 30 on penultimate whorl of holotype). Body whorl angularly inflated above, but abruptly becomes narrower anteriorly, forming a moderately long, pointed and nearly straight anterior siphonal canal. Body whorl sculpture consisting of spiral cords, but very weak sigmoidal axial ribs sometimes occur, and axial ribs disappeared near boundary of penultimate and body whorls, where a prominent spiral round topped keel appears. Aperture narrow and lenticular. Outer lip extended into a bifurcated spine. Posterior spine long and narrow, extending slightly downwards initially but gradually turning upward, regularly curved, and becomes ... posterior end. Posterior spine also curved ventrally. Anterior spine narrow, moderately long, extends obliquely downwards and encounters posterior spine almost right angle."
Locus typicus: Northern coast of Kimigahama, Ashikajima-cho, Choshi City, Choshi District, Chiba Prefecture, Japan
Stratum typicum: Kimigahama Formation, Barremian, Cretaceous
Perissoptera elegans Kase, 1980 holotype, Coll. National Museum of Nature and Science,Tokyo NSM PM15045, photo Takuma Haga
References:
- K. Amano, R.G. Jenkins, 2014. A new Paleocene species of Aporrhaidae (Gastropoda) from eastern Hokkaido, Japan; Paleontological Research, 18(1), 33-39
- Kase & Maeda, 1980. Early Cretaceous Gastropoda from the Choshi District, Chiba Prefecture, Central Japan. Trans. Proc. Palaeont. Soc. Japan, N.S., No. 118, p. 291-324
