Semicassis pyrum

Semicassis pyrum
	A shell of Semicassis pyrum, lateral view
Scientific classification
Kingdom:	Animalia
Phylum:	Mollusca
Class:	Gastropoda
Subclass:	Caenogastropoda
Order:	Littorinimorpha
Family:	Cassidae
Genus:	Semicassis
Species:	S. pyrum
Binomial name
	Semicassis pyrum; (Lamarck,1822)
Synonyms
	† Cassidea multisecta H. J. Finlay, 1924; Cassidea stadialis Hedley, 1914 ; Cassis nivea Brazier, 1872; Cassis pirum; Cassis pyrum Lamarck, 1822; † Cassis striatus F. W. Hutton, 1873; Cassis tumida Petterd, 1886; Phalium pyrum (Lamarck, 1822); Phalium stadiale (Hedley, 1914); Semicassis (Semicassis) pyrum (Lamarck, 1822); Semicassis pyrum f. hamiltoni (A. W. B. Powell, 1928); Semicassis pyrum pyrum (Lamarck, 1822); Xenogalea denda Cotton, 1945; Xenogalea finlayi Iredale, 1927; Xenogalea halli Cotton, 1954; Xenogalea mawsoni Cotton, 1945; Xenogalea powelli H. J. Finlay, 1928; Xenogalea pyrum (Lamarck, 1822); Xenogalea spectabilis Iredale, 1929; Xenogalea stadialis (Hedley, 1914); Xenogalea wilsoni Cotton, 1954; Xenophalium (Xenogalea) abernethyi Dell, 1956; Xenophalium (Xenogalea) matai A. W. B. Powell, 1952; Xenophalium abernethyi Dell, 1956; Xenophalium finlayi (Iredale, 1927); Xenophalium hamiltoni A. W. B. Powell, 1928; Xenophalium harrisonae A. W. B. Powell, 1928; Xenophalium matai A. W. B. Powell, 1952; Xenophalium pyrum (Lamarck, 1822); Xenophalium pyrum pyrum (Lamarck, 1822); Xenophalium wanganuiense A. W. B. Powell, 1928;

Semicassis pyrum, common name the "pear bonnet" or "common helmet", is a species of large sea snail, a marine gastropod mollusc in the family Cassidae, the helmet shells, bonnet shells and their allies.

Description

The shell has a light colour with a biconic shape, a notable large aperture, and ridges along the spire.

References

^ Powell, A. W. B. (1952). "New Zealand Molluscan Systematics, with Descriptions of New Species, Part 1". Records of the Auckland Institute and Museum. 4: 169–185. ISSN 0067-0464. JSTOR 42906061. Wikidata Q58676734.
^ "Semicassis pyrum (Lamarck, 1822)". WoRMS. World Register of Marine Species. Retrieved 28 October 2025.

Powell A. W. B., William Collins Publishers Ltd, Auckland 1979 ISBN 0-00-216906-1
"Semicassis pyrum". Gastropods.com. Retrieved 16 January 2019.

Media related to Semicassis pyrum at Wikimedia Commons

[1] Powell, A. W. B. (1952). "New Zealand Molluscan Systematics, with Descriptions of New Species, Part 1". Records of the Auckland Institute and Museum. 4: 169–185. ISSN 0067-0464. JSTOR 42906061. Wikidata Q58676734.

[2] "Semicassis pyrum (Lamarck, 1822)". WoRMS. World Register of Marine Species. Retrieved 28 October 2025.

[2]

[1]

Semicassis pyrum

A shell of Semicassis pyrum, lateral view
Scientific classification
Kingdom:	Animalia
Phylum:	Mollusca
Class:	Gastropoda
Subclass:	Caenogastropoda
Order:	Littorinimorpha
Family:	Cassidae
Genus:	Semicassis
Species:	S. pyrum
Binomial name
*Semicassis pyrum* (Lamarck,1822)
Synonyms^[2]
† Cassidea multisecta H. J. Finlay, 1924 Cassidea stadialis Hedley, 1914 Cassis nivea Brazier, 1872 Cassis pirum Cassis pyrum Lamarck, 1822 † Cassis striatus F. W. Hutton, 1873 Cassis tumida Petterd, 1886 Phalium pyrum (Lamarck, 1822) Phalium stadiale (Hedley, 1914) Semicassis (Semicassis) pyrum (Lamarck, 1822) Semicassis pyrum f. hamiltoni (A. W. B. Powell, 1928) Semicassis pyrum pyrum (Lamarck, 1822) Xenogalea denda Cotton, 1945 Xenogalea finlayi Iredale, 1927 Xenogalea halli Cotton, 1954 Xenogalea mawsoni Cotton, 1945 Xenogalea powelli H. J. Finlay, 1928 Xenogalea pyrum (Lamarck, 1822) Xenogalea spectabilis Iredale, 1929 Xenogalea stadialis (Hedley, 1914) Xenogalea wilsoni Cotton, 1954 Xenophalium (Xenogalea) abernethyi Dell, 1956 Xenophalium (Xenogalea) matai A. W. B. Powell, 1952 Xenophalium abernethyi Dell, 1956 Xenophalium finlayi (Iredale, 1927) Xenophalium hamiltoni A. W. B. Powell, 1928 Xenophalium harrisonae A. W. B. Powell, 1928 Xenophalium matai A. W. B. Powell, 1952^[1] Xenophalium pyrum (Lamarck, 1822) Xenophalium pyrum pyrum (Lamarck, 1822) Xenophalium wanganuiense A. W. B. Powell, 1928