Helcionopsis

Helcionopsis; Temporal range: Silurian PreꞒ Ꞓ O S D C P T J K Pg N
	Drawing of dorsal view of the shell of Helcionopsis radiatum. Head region is on the left.
	Drawing of lateral view of the shell of Helcionopsis radiatum. Head region is on the left.
Scientific classification
Kingdom:	Animalia
Phylum:	Mollusca
Class:	Monoplacophora
Order:	Tryblidiida
Superfamily:	Tryblidioidea
Family:	Tryblidiidae
Genus:	Helcionopsis; Ulrich & Scofield, 1897

Helcionopsis is an extinct genus of paleozoic monoplacophoran in the family Tryblidiidae.

The generic name is from the external resemblance which the genus bear to the recent species of the genus Helcion in family Patellidae.^[1]

Species

Species in the genus Helcionopsis include:^[2]

Helcionopsis radiatum (Lindström, 1884)
Helcionopsis reticulatus Easton, 1943^[3]
Helcionopsis striata Ulrich, 1897^[4]
Helcionopsis subcarinata Ulrich & Scofield, 1897^[5]

Shell description

General form and position of apex is as in Tryblidium, from which Helcionopsis differ in having the surface marked by fine radiating striae.^[1] Muscular scars of this genus Helcionopsis unknown in 1897, when the genus was described.^[1]

References

This article incorporates public domain text from reference.^[1]

^ ^a ^b ^c ^d ^e Ulrich E. O. & Scofield W. H. 1897. The Lower Silurian Gastropoda of Minnesota. In: Ulrich E. O., Scofield W. H., Clarke J. M. & Winchell N. H. The Geological and Natural History Survey of Minnesota, volume 3(2), Harrison and Smith, Minneapolis, 48 plates. Pages 813-1081, plates 61-82. Helcionopsis is on the page 821 and on pages 826-827.
^ Helcionopsis. The Paleobiology Database, accessed 25 August 2009.
^ Easton W. H. 1943. The Fauna of the Pitkin Formation of Arkansas. Journal of Paleontology 17(2):125-154.
^ Ulrich E. O. & Scofield W. H. 1897. The Lower Silurian Gastropoda of Minnesota. page 827, plate VXI, figure 29-30.
^ Ulrich E. O. & Scofield W. H. 1897. The Lower Silurian Gastropoda of Minnesota. page 827-828, plate VXI, figure 28.

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[Ulrich-1] Ulrich E. O. & Scofield W. H. 1897. The Lower Silurian Gastropoda of Minnesota. In: Ulrich E. O., Scofield W. H., Clarke J. M. & Winchell N. H. The Geological and Natural History Survey of Minnesota, volume 3(2), Harrison and Smith, Minneapolis, 48 plates. Pages 813-1081, plates 61-82. Helcionopsis is on the page 821 and on pages 826-827.

[2] Helcionopsis. The Paleobiology Database, accessed 25 August 2009.

[3] Easton W. H. 1943. The Fauna of the Pitkin Formation of Arkansas. Journal of Paleontology 17(2):125-154.

[4] Ulrich E. O. & Scofield W. H. 1897. The Lower Silurian Gastropoda of Minnesota. page 827, plate VXI, figure 29-30.

[5] Ulrich E. O. & Scofield W. H. 1897. The Lower Silurian Gastropoda of Minnesota. page 827-828, plate VXI, figure 28.

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