and species of Silurian Radiata. 277 



arranged : vertical section composed of arched, irregular, vesi- 

 cular plates, curving gradually from the walls under the cen- 

 tre, small and numerous at the sides, considerably larger in 

 the middle. 



It is possible that Mr. Lonsdale^s second figure of Cystiphyllum 

 Siluriense, t. 16 bis, f. 2, may be a young group of this species, 

 as this figure by its narrow form, radiated cups, &c. seems totally 

 distinct from his fig. 1, which is the true type of his species ; — 

 a new specific name would be required for it in any case. 



Wenlock limestone of Wenlock. 



Caninia lata (M'Coy). 



Sp. Char. Young corallum very widely conic, attaining the adult 

 diameter of 3 inches at a height of about 2 inches, after which 

 it remains cylindrical for a height of several inches, marked 

 with irregular concentric obtuse undulations and small fim- 

 briated lines of growth ; in the young the radiating lamellre 

 ai'e alternately longer and shorter, but before reaching the 

 adult diameter, they are all thin and nearly equal, four or five 

 in a space of 3 lines at a diameter of 2 inches 9 lines (or 110 

 to 116 all round), connected by numerous transverse curved 

 vesicular plates; inner area formed of broad horizontal simple 

 diaphragms, which at a diameter of an inch extend almost 

 across the corallum to the exclusion of the outer vesicular and 

 radiated layer ; at a diameter of 2^ to 3 inches they maintain 

 a diameter of about an inch, the outer lamellated and vesicular 

 zone having proportionately increased ; each of the diaphragms 

 is strongly bent downwards at one point of the circumference, 

 forming a distinct siphon ; outer wall extremely thin, forming 

 a few root-hke tubercles on the conical young ; terminal cup 

 with a depressed flattened centre and very convex outer area. 



In the Wenlock limestone of Wenlock. 



Clisiopkyllum vortex (M'Coy). 



Sp. Char. Corallum simple, conic, slightly curved, enlarging at 

 the rate of 1 inch 8 lines in 3 inches from the apex ; outer wall 

 thin, faintly marked with subequal longitudinal lamellar striie 

 (five or six in the space of 3 lines at a diameter of 1 inch) and 

 small concentric wrinkles ; at a diameter of 1 inch the hori- 

 zontal section shows an outer area of about sixty thick, equal, 

 radiating lamellse barely reaching one-fourth of the diameter 

 towards the centre, connected by small irregular transverse 

 vesicular plates ; a few of the pairs have a very thin, short, 

 marginal lamella between each of the larger ones, and where 

 this occurs, the vesicular transverse plates become much more 



