PLATE ()4. 



Pier. 1. "296. 1. Platynotus trentonensis. (Pag- 235.) 



1 a, h. Portions of the buckler and caudal shield of this species. 

 1 e. A fragment of the buckler, more compressed than the preceding. 

 1 d. A magnified portion of the crust, showing the pustules upon the surface. 



1 e. This figure is from a plaster cast of a specimen from the Blue limestone of Ohio. 



Fin'. ± 297. 2. Calymene becku. (P"8- 237.) 



'i «. .-Vn imperfect specimen, preserving the thorax and caudal shield, and tlie left maxillary portion of the' 

 buckler. 



2 4. A perfect specimen, with the exception of the maxillary portions, which are separated at the facial suture. 

 2 c. A similar specimen, preserving the maxillai-y parts, which give a difi'erent outline to the cephalic shield. 

 2 d. Part of a single articulation enlarged, sliowing the spine upon the centre, with papillose surface. 



2 e. A portion of the surface of the buckler enlarged, showing the papillose character of the surface. 



Fig. 3. 298. 3. Calymene sENAKiA. (Pag. 238.) 



3 o. A large s\)ecimen from tlie Trenton limestone, witli the buclcler abruptly curved downward in front. 

 3 4. A small specimen from the same rock. 3 c. Lateral view of the same. 



3 d. A small specimen from the Hudson-river group. 



3 e,f, g. Three views of a contracted specimen from the Blue limestone of Ohio. 



3 /(. Lateral view of the eye of this species, enlarged. The eye is obtusely conical, with a depression or cavity 

 at the apex, which is granulated as shown in 3 i. From the oblique conical form, this depression opens 

 outwards and upwards, being protected on all sides by a tliick crust. 



3 k. The buckler of this species separated at the facial sutures, showing the form of the maxillary portions 

 7 /, which embrace more than half the oculiform tubercle. 



3 I. Front view of the buckler, showing the termination of the facial sutures. ^ is the labrum, which occu- 

 pies this position beneath the buclcler. 



3 in. The same enlarged, showing the lines of the frontal suture, and the termination of the facial sutures. 



3 n. The inside of the glabella, having the maxillary and basal portions separated. 



Fio-. 4. 299. 1. AciDAspis tkentonensis. (Pag. 240.) 



1 a. Front view of the specimen, which is folded (natural size). 



1 b. The same enlarged, to show more distinctly this part of the fossil. 



4 c. Dorsal view (natural size). 4 d. The same enlarged. 



4 e. The caudal extremity and part of the (liorax enlarged. 



4 /. Margin of the maxilla; enlarged. 



Fifi. 5. 300. 2. AciPASPis .spinigei;. (Pag- 2-11.) 



Fig. 6. 305. 2. PiLACop.-^ !' LATicAUDVs. (Pag. 248.) 



