258 
SIREXOIDEI. 
ic appears to the present writer that the so-called C. imbricatus , 
C. ellipticus, <fec., are founded upon variously abraded dental plates. 
The dental plates of the Bohemian Permian variety frequently 
exhibit one or two small posterior coronal ridges more than is 
usual in the typical form. 
Form. Sf Loc. Coal-Measures: Northumberland, Yorkshire, and 
Staffordshire, England; Lanarkshire, Scotland. Lower Permian : 
Bohemia. 
45852. Hinder portion of cranial roof described and figured by T. 
P. Barkas, Coal. Meas. Palaeont. p. 113, fig. 244; Low 
Main Seam, Newsham, near Newcastle-upon-Tyne. 
Purchased, 1874. 
P. 3387. Imperfect bone resembling the hinder median occipital of 
the preceding specimen ; Newsham. Enniskillen Coll. 
47478. Similar bone ; Lower Permian, Khun ova, Bohemia. 
Purchased , 1876. 
41632, 43497 a. Two opercula; Newsham. 
Presented by T. P. Barkas , Esq., 1869,1872. 
P. 3386-7. Two opercula; Newsham. Enniskillen Coll. 
(i.) Palatine dental plates. 
45853, 45856. Palato-pterygoid with dental plate of right side; 
also a much abraded dental plate; Coal-Measures (Low 
Main Seam), Newsham, near Newcastle-upon-Tyne. 
Purchased, 1874. 
41627, 48999. Two abraded examples ; Newsham. 
Presented by T. P. Barkas, Esq ., 1869, 1876. 
P. 768. Two examples, slightly abraded; Newsham. 
Egerton Coll. 
P. 771. Bight and left palato-pterygoids with dental plates; 
(?) Newsham. Egerton Coll. 
P. 3376, P. 3379, P. 3381. Left palato-pterygoid with dental plate ; 
also four abraded dental plates ; Newslam. 
Enniskillen Coll. 
P. 5235. Abraded left dental plate ; Coal-Measures, Tividale. 
Purchased, 1886. 
39249-50. Two dental plates ; Coal-Measures, Airdrie, Lanarkshire. 
Purchased, I860. 
