36 
Horizon and Locality. — All the Bohemian species come from the 
Silurian limestone of Konieprns. I have seen it in a piece of olive-coloured 
arcrillaceons rock from Tarralumla, in which it is associated Avith numerous 
fragments of Trilohites and a branch of Alveolites repeats, Bough.. 
Order — TRILOBITA. 
Genus — ILLiBNU S, Lahnan. 
Illasnus Wahlenbergi ? J. Barrande. 
Illcenus JVallleilhergi, J. Barrande, 1816, Nouv. Trilob., p. 13. 
5, suhMangularis, Hawle and Corda, 1817, Prodr. einer Mon. Bolim. Trilob., pi. 3, 
fig. 29. 
,, JVaJllenbergianilS, J. Barrande, 1852, Syst. Sil. Bobeme, I, p. 681, pi. 31, fig, 19-21. 
It is not without doubt that I refer the single pygidium of an Illmnus 
sent to me to the species that Barrande has dedicated to Wahlenberg. This 
doubt can bo removed only by the discovery of complete specimens ; never- 
theless, even if the species be different, it will be closely allied to it 
[ Walilenl}ergV\ from the fact that the characters as given by Barrande agree 
perfectly Avith those of the specimen I have. In detail, this pygidium, which 
is only three millimetres long by two lu’oad, has practically the outline of an 
equilateral triangle Avitli strongly-rounded angles, and for which the end of 
the thorax serves as a base. It is fairly regularly arched, and the surface is 
quite smooth. Bour segments of the thorax remain connected to it. 
Horizon and Locality. — It occurs in a A^dlitc crystalline limestone, 
A'eined AAutli red, at Boree Cave. 
de/ms— STAUBOCEPIIALIJS, J. Barrande. 
Staurocephalus Clarkei, L. G. de Koninck. 
PI. I, fig. 8.^ 
Although I am acquainted Avith the impression of the head and 
pygidium of this species only, the form and characters are suthcient to 
convince me that it differs from all its congeners at jiresent knoAvn. 
1 PI. I, figs. 13, 13a.— AV.S.D.] 
