92 SYSTEMATIC ARRANGEMENT 



6. Ph. odontocephalus ; Protuberantia frontali antice ovata, lobo sccuudo coustricto ; limbo ante 

 protuberantiam octies dentato. Table IV, Fig. 4. 



Ee/. — Calym. odontocephala, Gkeen, Sill. Am. Jourii. vol. xxv, p. 334. Harlan, Med. 

 and Pliys. Res. 30 1 . 



Loc. — In a gray sandstone at Ulster, New York, U. S. I saw the plaster cast of a 

 cephalic shield of this species at Berlin. 



The glabella is short at its anterior extremity, ovate, moderately convex ; the second 

 lobe is reniform, almost isolated, only connected with the central axis by a short peduncle ; 

 the third is a narrow transverse protuberance, behind which there follows a fourth broader 

 one, perfectly resembling the margin of articulation. The large eyes correspond with the 

 kidney-shaped prominence ; they reach neither to its anterior nor to its posterior extremity, 

 and are far removed from the external margin. A broad flat border encircles the latter, in 

 which may be distinguished anteriorly, and placed in front of the glabella, eight obtuse 

 indentations, inclosed by an impressed furrow (? of the facial suture). The posterior angles 

 of the specimen were indistinct, but appeared to be obtuse ; body and caudal shield are 

 wanting. 



Sub-group (i.) The extremity of the pygidium sharply angulated. 



7. Ph. macrophthahnus ; Lobo autico capitis acutangulo, lobis sequentibus sequalibus ; rliaclii caudse 

 10-12 articulata, scuto in apice acuminato. Long. 1-1J4". 



Bef. — Cahjmene macr. Brongn. Crust, foss. 14, PI. I, Fig. 4, A, B. Milne Edw. Crust. 



iii, 323. Pander, Beitr. 138, Tab. IV, B, Fig. 8 ; Tab. V, Fig. 5 ; Tab. VI, Fig. 



9. C. Bowningi(B, Murchison, Ä7. Sgst. ii, 655, PI. XIV, Fig. 3. Buckl. 



Bridg. Tr. PI. XLVI, Fig. 5. Milne Edwards, Crust, iii, 324. 12. 



Loc. — The older transition limestone of Huraandiere in Brittany, and in the Petersburg 



hüls. 



This species approaches very near to C. sderops in point of habit, but is much more 

 slender ; the glabella is similarly four-lobed, and the eyes are much larger, almost as large 

 as in Ph. rotundifrons. The anterior lobe of the glabella is obliquely rhombic, rather 

 acutely angular at the anterior part ; the three following lobes between it and the margin 

 of articulation become successively rather smaller, and the posterior lobe is the most 

 strongly arched among them. The prominent eyes reach from the anterior margin of the 

 cephalic shield to the posterior. The caudal shield, according to Pander, has from ten to 

 twelve joints in the axis, slight lateral ribs, and a sliort but acute termination. 



8. Ph. rntundifrons : Tuberculo capitis antico ovato, lobis sccuiulis triangularibus, tertiis minutis 

 spii-ajformibus ; oculis maximis ; rhacbi caudali 7-8 anuulata, costis lateralibus sex. Long. 2". Table 

 IV, Pig. 2. 



Bef. — Emmr. Dissert. 23. 10, c, Fig. Pleur. laciiiiatus, Romer, d. Blieiu. Uebergmigstel 

 83. 69. 2, Tab. II, Fig. 8 



Loc. — Described from an impression in plaster in the Museum at Berlin ; tlie original 

 was found at the Kalauerberg (in the Dietzhatze, in the Westerwald near Dillenburg). 



Exactly similar to the preceding species in its entire habit ; but the anterior large lobe 

 of the glabella rather more oblong and of a short egg-shaped form ; the second has the 



