PLATE 67. 
]. 307. 1. Tkinucleus concentricus. (Pag. 255.) 
1 a.- A large individual, destitute of spines upon the posterior angles of the buckler and glabella. The border 
in front of the glabella has three distinct rows of punctures, four in front of the cheeks, and five on 
each side, with six or seven near the base. 
1 b. The thorax and caudal shield enlarged, to show more clearly the character of the segments. 
1 c. A smaller specimen, preserving the spines of the buckler There are four rows of punctures in front, and 
six on each side of the buckler. 
1 d. The buckler, preserving the posterior spine of the glabella. 
1 e. Fragments of the cephalic border, showing a variable number of rows of punctures in front; one having 
five, with seven or eight at the posterior margin. 
1 /. A portion of the marginal fillet, where the crust is partially removed, showing the little studs or points 
which fill these pores from below. 
I g. A fragment of a large buckler, having but two distinct rows of punctures in front of the glabella. 
1 h. A portion of the thorax and caudal extremity, from the glazed slate at Waterford. 
2. 310. 1. Olenus asaphoides. (Pag- 256.) 
2 a. An imperfect cephalic shield, with several articulations. 2 b. A smaller imperfect cephalic shield. 
2 c. A fragment of one of the lateral articulations of the thorax. 
3. 311. 2. Olenus undulostriatus. (Pag- 258.) 
3 a. The fragment, natural size. 
3 b. A part of the same enlarged, showing the course of the facial suture, and the rugose striated glabella. 
4. 297. 2. Calymene beckii. (Pag. 250 .) 
4 a. The buckler, with a few of the articulations of the thorax. The specimen is very much compressed, and 
the crust removed. 
4 b. A specimen of the same fossil, presenting nearly the entire length of the individual. 
4 c. An impression of the body, showing the indentations produced by the short spines upon the back. 
4 d. A portion of the same enlarged, showing the impressions of the fine granulations of the crust. 
4 e. A fragment preserving an impression of a part of the central and one lateral lobe of this species. 
5. 312. 1. Agnostus lobatus. (Pag- 258.) 
5 a, b. Individuals of the natural size. 5 c, d. The same magnified. 
5 e, f. Specimens showing an articulation of the lobes. Magnified views. 
6. 313. 1. Thaleops (Ill^nus) ovatus. (Pag- 259.) 
6 a. The specimen of the natural size. The upper figure has a strong thick spine at the posterior angles of the 
cephalic shield. 
0 b. A part of the cephalic shield magnified, showing the punctures and the course of the facial suture. 
