| Home> Cenozoic> Holocene (Recent)> Nordic Seas>
 

List species

Euscenium corynephorum Jørgensen, 1900

Description - Add description

Euscenium corynephorum:
Has the four primary spines, about equally developed, and the ventral, sagittal one.

The main spines are broad, three-edged, broadest in the outer half. On each edge there are from 3 to 5, or more, strong slender pointed branches (spines), more or less distinctly scattered in comparison to those on the other edges of the same spine, only rarely here and there in distinct verticils.

Between the neighbouring branches or the different main spines, rather long and fine connecting beams extend, these being in their turn again connected by numerous similar ones. Thus a more or less perfect net is formed which is best developed between the apical spine (D) and the ventral, sagittal one. This network forms a rather imperfect lattice shell with meshes, very uneven in shape and size, from small, triangular and trapezoidal to very large, polygonal openings. Also the inner branches (spines) on the same main spine are connected, partly with the main spine itself, partly with each other, also by fine connecting beams, parallel to the direction of the main spine (as in the spines of Rhizoplegma boreale).

The meshes of the lattice shell strongly recall those of Cladoscenium tricolpium. Very often (in young individuals) so little of the network is developed that it would not be justifiable to consider the species as a Euscenium, if one did not occasionally find a well developed latice shell. Cfr. Jørgensen 1900.

This species is very different from Cladoscenium tricolpium, and without doubt is more closely allied to those forms which have an imperfect lattice shell (Plectoidea HCK.). It might be classed as belonging to the genus Periplecta HCK., if it were not for the distinct, ventral, sagittal spine. (This spine was previously overlooked, and for this reason is not mentioned in my earlier description of the species [Jørgensen 1900] p. 77). I prefer at present to let it remain in the genus Euscenium, rather than to start a new genus, as the genus Euscenium HCK. certainly requires revision.
Jørgensen 1905


Description

 

Images

 

Synonyms

 

References

 

Distribution

 

Discussion / Comments

 

Web links