PLATE XXIV. 



CARADOC ROCKS. 



Fio-s. 1 — 5. AsapJius {Isotelus) gigas, Dekay. From the Caradoc Rocks of Tyrone. 



(Mus. Pract. Geology.) 



1. „ „ „ Young specimen, showing labrum. (Portlock's 



/. planus, pi. viii, fig. 1.) 



2. „ „ „ Larger head. (Portlock's specimen, /. ,se/eroj05, 



pi. X, fig. 2.) 



3. „ „ „ Tail of a large specimen. 



4. „ „ „ Quite young. (7. ovatm, Portlock, pi. viii, 



fig. 5.) 



5. „ „ „ Free cheek, showing eye and cast of lateral 



tubercle {a). <^ Is a cast in sealing-wax 

 of the same outer portion of the cheek, 

 showing the pit for the reception of the 

 pleurae in rolling up. (Portl.,pl. vii, fig. 4.) 



UPPER TREMADOC ROCKS. 



Figs. 6 — 12. Asaphus [Isotelus?) Homfragi, Salter. (From Mr. D. Homfray's 



cabinet, and Mus. P. Geology.) 



6. „ „ „ Elongated and compressed specimen. 



7. „ „ ,, Young individual. 



8. „ „ ,, Labrum and epistome ; the latter less perfect. 



9. „ „ ,, Labrum, pressed out of shape. 



10. „ „ „ Tail, shortened by pressure, and showing the 



rudimentary rings on ^xis and sides. 



11. „ „ „ Another specimen, similarly compressed. 



12. „ „ ,, Specimen shortened obliquely. 

 All the Tremadoc Slate specimens are from Garth, Portmadoc. 



Figs. 13, 14. Asaphus [Isotelus ?) a finis, M.'Q/OY. Young and older specimen. (Mr. 



Ash's cabinet.) 



