1853.] RIBEIRO AND SHARPE — BUSSACO. 159 



the character relied on by Mr. Sharpe for the distinction of /. Lusi- 

 tanictis, namely the shape of the glabella and head, is due to pressure, 

 as the better specimens we now possess show clearly. Pl. VII. 

 fig. I shows the smallest of the specimens collected, and appears not 

 to have been altered (as many of the others have been) in form. 



Illaenus Lusitanicus, therefore, of the former list, vol. v. pp. 146 & 

 150, pl. 6. fig. 1, is regarded by me as a synonym of/, giganteus, 

 Burm., and of J. Desmaresti of M. Rouault. 



2. Placoparia ZippeiiCoxdia), Trilobites Zippei of Boeck (PL VII. 

 figs. 2, a — e). This agrees in nearly all particulars with the descrip- 

 tion and figure lately given by M. Corda, Prodrome Tril. Boheme, t. vi. 

 f. 71. In Barrande's figure*, however, which is strictly correct, the 

 front of the head does not extend so far forwards beyond the glabella, 

 and is therefore still more like ours. Both authors figure and de- 

 scribe twelve body rings, and in our specimen there are not more 

 than ten or eleven at most : and the convex lobes of the tail, though 

 exactly alike in form and number, both on the axis and sides, are 

 further apart from each other than in our Trilobite. This last 

 character is due to the Bohemian specimens being internal casts, while 

 ours (2 a) shows the external surface. And we take the opportunity 

 of figuring with it (2 b — d) a specimen from Vallongo formerly re- 

 ferred (vol. V. p. 146) to Cheirurus. The perfect tail, fig. 2 e, is also 

 from the latter locality. 



Placoparia differs from Cheirurus both in general habit and in 

 the reduced size of the front lobe of the glabella, and also in a pecu- 

 liarity in the cheeks, which somewhat below the minute eyes are 

 deeply grooved across (fig. 2 a) so as to cut off a small lobe which 

 lies parallel to the upper margin of the head and opposite the fore- 

 most lateral lobe of the glabella. The free cheeks are very small 

 and narrow, and the eyes minute and forward. The axis of the tail 

 has five, while Cheirurus has but four rings — the terminal one, how- 

 ever, is very minute. 



3. We prefer to give the name Phacops procBvus, Emmr., to the 

 species which is so abundant in Bohemia, and which is now more 

 generally known as P. socialis, Barrande. There is no doubt of the 

 identity of the species. 



4. Another Phacops occurs with the last at Bussaco which nearly 

 resembles it, but has the head quite pointed in front, and consider- 

 ably inflated there, while the upper glabella furrows are almost ob- 

 solete ; the tail that accompanies it has fewer ribs than that of P. 

 procBvus, and is drawn out into a broader and thicker point. Our 

 specimens are not good enough to figure. 



5. 6. Calymene Tristani and C. Arago occur in very good condition, 

 the latter distinguished easily by the smooth sides to the tail. Both 

 are also found in Spain. 



7. Trinucleus Pongerardi, Rouault. We have no specimens which 

 show the branched head-spines, all the specimens having simple 

 spines directed straight backwards. But the fringe is inflated f and 



* Syst. Sil. de Boheme, pl. 29. f. 30-38. 



t In the common British species, T. concentricus {Caractaci, Sil. Syst.), the 

 upper surface of the fringe is flat, and the lower side angular. 



