PLATE 65. 

 Fig. 1. 301. 2. Ceraurus pleurexanthemus. (Pag. 242.) 



1 a. A nearly entire specimen, with the maxillary portions obscure or entirely removed. The buckler is par- 

 tially crushed and obscured by soft shaly matter, and the oculilbrm tubercle very imperfectly preserved. 

 The posterior prolongations of the buckler are distorted and obscure, as are also the spines proceeding 

 from the caudal shield. 



I b. A specimen of the same partially folded, with the buckler curved forward and tlie margin broken oO'. 

 The crust is partially exfoliated, so tliat the surface markings are not well preserved. 



i c. Front view of the buckler, showing the junction of the epistoma. 



1 (/. A large imperfect sjiecimen, showing more distinctly the peculiar structure of the articulations. Tlie 

 buckler is imperfect, but still partially preserves the posterior spines : the caudal spines are broken ofl'. 

 (This specimen has been left by the engraver imperfectly represented.) 



1 c. Lower side of the buckler of the last, showing the epistoma joined by a straight suture to the front of the 

 glabella. 



i f. A separated labrum, with the upper margin broken off. 1 g. A buckler, with the maxillae removed. 



1 h, i. The glabellae of two large individuals. 1 i*. A magnified portion of the surface. 



1 k. A caudal shield, with the spines removed. 



I /. The spines of the caudal extremity, with a single articulation connecting them. View from the lower side. 



1 m. The caudal shield, with the spines attached. 1 ni*^ A magnified portion of the surface. 



1 n. A transverse section, showing the elevation of a segment, and the lateral extension of the articulations 



into fin-like processes. 



Fig. 2. 302. 3. Ceraurus vigilans. (Pag- 245.) 



2 a. An entire specimen, preserving the posterior spines of the buckler. 



2 ft. Front view of the same, showing the elevation of the oculiferous tubercles. 

 2 c. A small specimen with the surface markings obscure. 



2 d. Lateral view of a specimen, showing the extension of the extremities of the lateral articulations. 



2 e. Caudal shield of a larger individual. 



2/. An enlarged poi-fion of the buckler of 2 a, showing pustulose tubercles. 



'2 g. The caudal shield and a portion of the thorax enlarged, showing the tubercles upon alternate and third 

 segments. 2 h. Profile of the same. 



Fig. 3. 304. 1. Phacops callicephalus. (Pag: 247.) 



3 a. Cephalic shield of this species. 3 ft. A small entire specimen. 

 3 c. The caudal shield of the last, showing the number of articulations, etc. 



3 d. Magnified portion of tlie surface of the buckler, showing the pustulose-punctate character of Ihe surface. 



3 e. A magnified portion of the articulations of the thorax, showing the irregular pustulose surface. 



3/. Lateral view of the eye of this species. 3 g. Magnified view of the eye. 



3 h. A contracted specimen. The lobes of the glabella are obliterated, and the surface of the eye crushed or 



absorbed. 

 3 /'. View of the same specimen, showing the caudal shield and front of the buckler. 



Fig. 4. 307. 1. Trinucleus concentricus. (Pag- 249.) 



■ I n. The cephalic shield of this species, still preserving one of the slender spines from the jiosterior angle. 



Tlic posterior spine of the glabella is broken off, though the fracture is not conspicuous. 

 -1 ft. Lateral view of the cephalic shield of a smaller specimen. 

 4- f. The cephalic shield of a small specimen, in which the glabella preserves its posterior spine. 



