"Tangential section of a larva of Astroides calicularis which has fixed itself on a piece of cork. ec, Ectoderm; en, endoderm; mg, mesogloea; m, m, mesenteries; s, septum; b, basal plate formed of ellipsoids of carbonate of lime secreted by the basal ectoderm; ep, epitheca." — The Encyclopedia Britannica, 1910

Astroides Calicularis

"Tangential section of a larva of Astroides calicularis which has fixed itself on a piece of cork. ec,…

Combination of holohedral tetragonal forms.

Combination of Tetragonal Prism and Basal Pinacoid

Combination of holohedral tetragonal forms.

"Cryptostemma Karschii, anterior aspect of the prosoma with the "hood" removed. I to IV, first to fourth appendages of the prosoma; a, basal segment of the second pair of appendages meeting its fellow in the middle line." — The Encyclopedia Britannica, 1910

Cryptostemma Karschii

"Cryptostemma Karschii, anterior aspect of the prosoma with the "hood" removed. I to IV, first to fourth…

A beryl crystal, an example of a basal pinacoid.

Beryl crystal

A beryl crystal, an example of a basal pinacoid.

A beryl crystal, an example of a basal pinacoid.

Beryl crystal

A beryl crystal, an example of a basal pinacoid.

A beryl crystal, an example of a basal pinacoid.

Beryl crystal

A beryl crystal, an example of a basal pinacoid.

A beryl crystal, an example of a basal pinacoid.

Beryl crystal

A beryl crystal, an example of a basal pinacoid.

"Hexagonal-rhombohedral. Crystals usually thick to thin tabular. Basal planes prominent, often showing triangular markings." — Ford, 1912

Hematite

"Hexagonal-rhombohedral. Crystals usually thick to thin tabular. Basal planes prominent, often showing…

"...shows a combination of a hexagonal prism (m) with the basal pinacoid (c)." -The Encyclopedia Britannica 1910

Hexagonal Prism and Basal Pinacoid

"...shows a combination of a hexagonal prism (m) with the basal pinacoid (c)." -The Encyclopedia Britannica…

"Holothyrus nitidissimus, one of the Acari; ater Thorell. A, Lateral view with appendages III to VI removed, I, plate covering the whole dorsal area, representing the fused tergal sclerites of the prosoma and opisthosoma; 2, similarly-formed ventral plate; 3, tracheal stigma. B, dorsal view of the same animal; II to VI, 2nd to 6th pairs of appendages. The 1st pair of appendages both in this and in C are retracted. C, Ventral view of the same; II to VI as in B; a, genital orifice; b, anus; c, united basal segments of the second pair of appendages; d, basal segment of the 6th prosomatic appendage of the right side. The rest of the appendage, as also of app. III, IV and V, has been cut away." — The Encyclopedia Britannica, 1910

Holothyrus Nitidissimus

"Holothyrus nitidissimus, one of the Acari; ater Thorell. A, Lateral view with appendages III to VI…

A modern sponge with silicious skeletal structure, and basal glass fibers for fixation (<em>Holtenia carpenteri</em>).

Holtenia Carpenteri

A modern sponge with silicious skeletal structure, and basal glass fibers for fixation (Holtenia

"Orthorhombic. Crystals commonly tabular parallel to basal plane, showing also short prisms and low brachydomes. The brachydomes usually striated parallel to the brachy-axis. Often twinned, given coxcomb and spear-shaped groups." &mdash; Ford, 1912

Marcasite

"Orthorhombic. Crystals commonly tabular parallel to basal plane, showing also short prisms and low…

"Upper aspect of the primordial cranium, with the membrane-bones removed. An, angular; ao, anteorbital; Ar, articulary; B, basal; D, dentary; E, ethmoid; F, frontal; Ma, mastoid; Mp, metapterygold; Mx, maxillary; N, nasal; O, operculum; Oc, occipital; Pa, parietal; Pl, palatine; Pmx, premaxillary; po, postorbital; Prf, prefrontal; Pt, post-temporals; Ptf, postfrontal; Ptr, pterygold; Q, quadrate; S, suspensorium; So, suboperculum; Sp, sphenold; Spl, splenial; St, supratemporals; T, tympanic lamina; Tu, turbinal; v, vomer; x x, small ossicles; x' x', spiraculars." &mdash; Encyclopedia Britannica, 1893

Polypterus Skull

"Upper aspect of the primordial cranium, with the membrane-bones removed. An, angular; ao, anteorbital;…

"Lower aspect of the primordial cranium, with the membrane-bones removed. An, angular; ao, anteorbital; Ar, articulary; B, basal; D, dentary; E, ethmoid; F, frontal; Ma, mastoid; Mp, metapterygold; Mx, maxillary; N, nasal; O, operculum; Oc, occipital; Pa, parietal; Pl, palatine; Pmx, premaxillary; po, postorbital; Prf, prefrontal; Pt, post-temporals; Ptf, postfrontal; Ptr, pterygold; Q, quadrate; S, suspensorium; So, suboperculum; Sp, sphenold; Spl, splenial; St, supratemporals; T, tympanic lamina; Tu, turbinal; v, vomer; x x, small ossicles; x' x', spiraculars." &mdash; Encyclopedia Britannica, 1893

Polypterus Skull

"Lower aspect of the primordial cranium, with the membrane-bones removed. An, angular; ao, anteorbital;…

"Side view, with the membrane-bones. An, angular; ao, anteorbital; Ar, articulary; B, basal; D, dentary; E, ethmoid; F, frontal; Ma, mastoid; Mp, metapterygold; Mx, maxillary; N, nasal; O, operculum; Oc, occipital; Pa, parietal; Pl, palatine; Pmx, premaxillary; po, postorbital; Prf, prefrontal; Pt, post-temporals; Ptf, postfrontal; Ptr, pterygold; Q, quadrate; S, suspensorium; So, suboperculum; Sp, sphenold; Spl, splenial; St, supratemporals; T, tympanic lamina; Tu, turbinal; v, vomer; x x, small ossicles; x' x', spiraculars." &mdash; Encyclopedia Britannica, 1893

Polypterus Skull

"Side view, with the membrane-bones. An, angular; ao, anteorbital; Ar, articulary; B, basal; D, dentary;…

"Lower aspect of the skull, part of the bones being removed on the side. An, angular; ao, anteorbital; Ar, articulary; B, basal; D, dentary; E, ethmoid; F, frontal; Ma, mastoid; Mp, metapterygold; Mx, maxillary; N, nasal; O, operculum; Oc, occipital; Pa, parietal; Pl, palatine; Pmx, premaxillary; po, postorbital; Prf, prefrontal; Pt, post-temporals; Ptf, postfrontal; Ptr, pterygold; Q, quadrate; S, suspensorium; So, suboperculum; Sp, sphenold; Spl, splenial; St, supratemporals; T, tympanic lamina; Tu, turbinal; v, vomer; x x, small ossicles; x' x', spiraculars." &mdash; Encyclopedia Britannica, 1893

Polypterus Skull

"Lower aspect of the skull, part of the bones being removed on the side. An, angular; ao, anteorbital;…

Holohedral orthorhombic combination

Prism and Basal Pinacoid

Holohedral orthorhombic combination

"A crystal of zincite with a prism terminated by a pyramid above a basal pinacoid below." &mdash; Ford, 1912

Zincite

"A crystal of zincite with a prism terminated by a pyramid above a basal pinacoid below." — Ford,…