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Micrhystridium echinoides
Original description: [Valensi, 1949, p. 544-545] (translated from French):
Micrhystridium echinoides nov, sp. 1 of fig. 5.
Holotype: Lower Bathonian, flint from Airvault (Deux-Sèvres).
The shell (1 of fig. 5) of generally spherical shape is regularly bristling with a large number of processes of equal length. Its
upper surface, the only visible one, is decorated with polygonal designs corresponding to the lines of insertion of the processes. Of a length equal to that of the radius of the shell, these are hollow, clearly widened at the base, and their cavity communicates with that of the shell; straight and strong overall, they can sometimes be flexuous with a more tapered end, their density is about ten over a length of 10 μ from the edge of the shell. The shell diameter is 17 μ, the processes are 9 μ long, which gives a wingspan of 35 μ.
The color of the only specimen of this beautiful species is dark brown.
So far this species has only been observed in the Lower Bathonian, it has no analogue in the Silurian and in the Cretaceous. It is very reminiscent of some Hystrichosphaeridium of the Hystrichosphaeridium striolatum DEFL. group (in the broad sense), whose dimensions are much larger (shell alone: 40 μ and more).
Micrhystridium echinoides nov, sp. 1 of fig. 5.
Holotype: Lower Bathonian, flint from Airvault (Deux-Sèvres).
The shell (1 of fig. 5) of generally spherical shape is regularly bristling with a large number of processes of equal length. Its
upper surface, the only visible one, is decorated with polygonal designs corresponding to the lines of insertion of the processes. Of a length equal to that of the radius of the shell, these are hollow, clearly widened at the base, and their cavity communicates with that of the shell; straight and strong overall, they can sometimes be flexuous with a more tapered end, their density is about ten over a length of 10 μ from the edge of the shell. The shell diameter is 17 μ, the processes are 9 μ long, which gives a wingspan of 35 μ.
The color of the only specimen of this beautiful species is dark brown.
So far this species has only been observed in the Lower Bathonian, it has no analogue in the Silurian and in the Cretaceous. It is very reminiscent of some Hystrichosphaeridium of the Hystrichosphaeridium striolatum DEFL. group (in the broad sense), whose dimensions are much larger (shell alone: 40 μ and more).