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Acastella
Classification
Phylum:
Arthropoda
Subphylum:
Trilobitomorpha
Class:
Trilobita
Order:
Phacopida
Suborder:
Phacopina
Superfamily:
Dalmanitacea
Family:
Dalmanitidae
Subfamily:
Acastavinae
Formal Genus Name and Reference:
Acastella REED, 1925
Type Species:
Acaste downingiae spinosa SALTER, 1864
Images
(Click to enlarge in a new window)
Fig. 376, 2. *A. spinosa (Salter), Sil.(U. Ludlow), Eng., ceph., x2 (255), Fig. 377, 2. A. tiro Richter & Richter, L.Dev., Ger.(Ebbe), 2a, b, ceph., pyg., internal molds showing inner denticulations on pygidium, x4.3 (255)
Synonyms
Geographic Distribution
Eu.
Age Range
Beginning Stage in Treatise Usage:
U.Sil.
Beginning International Stage:
Gorstian
Fraction Up In Beginning Stage:
0
Beginning Date:
426.74
Ending Stage in Treatise Usage:
L.Dev.
Ending International Stage:
Emsian
Fraction Up In Ending Stage:
100
Ending Date:
394.3
Description
Cephalic frontal margin visible from above, pointed, axial furrows only slightly diverging, 3p lateral glabellar furrows directed backward, 1p and 2p deep, transverse, 1p not continuous, curved backward, with inner ends bending forward, eyes large, genal angles with spines. Hypostoma with maculae near margin. Pygidium broadly triangular, with terminal spine, about 7 axial rings and 4 ribs, margin tending to develop interior denticles.
References
Museum or Author Information
Classification
Phylum:
Arthropoda
Subphylum:
Trilobitomorpha
Class:
Trilobita
Order:
Phacopida
Suborder:
Phacopina
Superfamily:
Dalmanitacea
Family:
Dalmanitidae
Subfamily:
Acastavinae
Formal Genus Name and Reference:
Acastella REED, 1925
Type Species:
Acaste downingiae spinosa SALTER, 1864
Images
(Click to enlarge in a new window)
Fig. 376, 2. *A. spinosa (Salter), Sil.(U. Ludlow), Eng., ceph., x2 (255), Fig. 377, 2. A. tiro Richter & Richter, L.Dev., Ger.(Ebbe), 2a, b, ceph., pyg., internal molds showing inner denticulations on pygidium, x4.3 (255)
Synonyms
Geographic Distribution
Eu.
Age Range
Beginning Stage in Treatise Usage:
U.Sil.
Beginning International Stage:
Gorstian
Fraction Up In Beginning Stage:
0
Beginning Date:
426.74
Ending Stage in Treatise Usage:
L.Dev.
Ending International Stage:
Emsian
Fraction Up In Ending Stage:
100
Ending Date:
394.3
Description
Cephalic frontal margin visible from above, pointed, axial furrows only slightly diverging, 3p lateral glabellar furrows directed backward, 1p and 2p deep, transverse, 1p not continuous, curved backward, with inner ends bending forward, eyes large, genal angles with spines. Hypostoma with maculae near margin. Pygidium broadly triangular, with terminal spine, about 7 axial rings and 4 ribs, margin tending to develop interior denticles.