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Phorticium pylonium Haeckel, 1887

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Phorticium pylonium:
Cortical shell irregular, roundish, about three times as large as the enclosed lentelliptical, regular, Larnacilla-shell, connected with it by some radial beams and irregularly latticed girdles; between these remain four to eight large open gates of irregular roundish form and size; and these gates are the same as on Tetrapyle and Octopyle. This very variable species may be regarded as a monstrosity of those genera of Pylonida; it is very common, but all individuals are more or less unequal; some specimens approach to some common species of Tetrapyle. The surface of the shell is more or less spiny.

Dimensions: Diameter of the irregular cortical shell 0.12 to 0.18; length of the lentelliptical medullary shell 0.05 to 0.06; breadth 0.035 to 0.45.
Habitat: Cosmopolitan; Mediterranean, Atlantic, Pacific, &c. common, surface and in various depths.
Haeckel 1887
Phorticium clevei:
Complex latticed skeleton. Inner part composed of several chambers disposed in spiral. Width of chambers in successive turns increasing greatly. Chambers not with continuous walls, as in species related to genus Lithelius but are as it were made lighter: only the middle part remains. This leads to formation of arches. Direction of spiral along which chambers are disposed alters and therefore structure of shell difficult to draw schematically. Altogether not more than five marked turns. Chambers crossed by numerous radial cross pieces projecting to the outside (usually broken off). Pores unequal in size, varying in shape, disposed irregularly.

Growth of shell begins from central, more compact part. Then apophyses forming on radial needles give rise to walls of subsequent wider turns. Young specimens with very dense spiral greatly differentiated from adults, more, complex structure of shell causes it to appear differently when viewed from different sides: in two basic positions is appears almost symmetrical, but obliquely spiral arrangement of chambers is clearly seen.

Dimensions: largest diameter of shell with five turns up to 200 micrometer, central oval core in which four turns clearly seen has largest diameter of about 100 micrometer, and smallest of about 80 micrometer. Diameter of pores on fourth turn 5-15 micrometer.
Petrushevskaya 1967


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