A Monograph of the Trilobites of North America: with Coloured Models of the Species — John Shaqi
A Monograph of the Trilobites of North America: with Coloured Models of the SpeciesGreen, Jacob
Science
A Monograph of the Trilobites of North America: with Coloured Models of the Species
Green, Jacob
Paleontology -- North America; Trilobites -- North America
Outline of the buckler hemispherical, the edge surrounded by a
semicircular border of tessellated or rounded punctures, in three
concentric rows in front--on each side near the posterior angle of the
buckler, these rows of punctures are more numerous; the front is highly
convex; is rounded before, and gradually tapers towards the abdomen.
The cheeks form spherical triangles, and are entirely destitute of
oculiferous tubercles or any other markings; their posterior angles
project beyond the sides of the abdomen. Abdomen and tail very much
compressed, and composed of about ten articulations; costal arches of
the lateral lobes grooved; tail attenuated. Whole length half an inch.
The Cryptolithus Tessellatus, resembles a good deal the Entomostracites
Granulatus of Wahlenberg, and which Dr. D aim an calls Asaphus
Granulatus. The figure of this animal given by Brongniart, table 3,
fig. 7, appears to be quite imperfect, and is very unlike, except
in the buckler, the representation of Wahlenberg's fossil, given by
Dalman, table 2, fig. 6. Though the angles of the buckler in the
Asaphus Granulatus are much more elongated than those of the C.
Tessellatus, it may perhaps be another species of the same genus.[43]
[Footnote 43: The following, is Dr. Dalman's description of the Asaphus
Granulatus:--
A. trunco sexarticulato pygidioque lævibus, capite antice
semicirculari margine granuloso, angulis posticis extensis corpore
longioribus.
Animalculum singulare, inversum si inspicitur, lyram forma fere
similans. Caput antice semicirculare, margine distincto, serie
submoniliformi e granulis approximatis ornato, discus capitis
lævis, sed ambitus intra marginem punctis elevatis obsitus. Hic
ambitus, una cum margine, truncum quoque amplecti videtur, ad
pygidii basin usque, ubi in cornua lævia, trunco multo longiora,
abit. Glabella antice fere clavæformis, ad basin utrinque emittens
lobi rudimentum. Truncus brevis lævis segmentis constans tantummodo
sex, rhachide angusta. Pygidium breve, rotundatum, læve; adeo
parvum ut ne quidem capitis disco respondeat.
Obs.--Oculos atque suturam facialem ex autopsia describere licet.
Vide Om. Palæaderna eller de sa kallade Trilobiterna af. J. W. Dalman,
pages 50-4. ]
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