88 POTERIOCRINID^.— POTERIOCRINUS. 



crinus. The specimen, from which our figure is taken, has been flattened by pressure 

 but it is sufficiently perfect, to prove tliat the proboscis was of large size. 



Figure 2 c, PI. 11. represents a specimen with the plates, which cause the open space 

 at the base of the rays, so frequently referred to, and which all the animals belonging to 

 this genus possess. The arrangement of these plates, is particularly worthy of obser- 

 vation, because a Poteriocrinns when viewed on opposite sides, appears so totally different, 

 that an unpractised observer, might consider two specimens of the same species as apper- 

 taining to animals, of even different genera. 



The root or base of attachment, is formed of several root like processes combined witli 

 irregular secretions of solid calcareous matter. 



14 Species. Poteriocrinus longidactylus. (Austin.) 

 PL 11, figure .3, a. 



Definition. — Body small and conicaJ ; main rays five, long, and articulating by the 

 whole breadtii of the plates, final divisions apparently forty; column long and enlarging 

 near its attachment to the body. 



Synonymes and References. 



Cumb. Trans. Geol. Soc. Vol. 5. PL 3. Fie/. 1. /;. 90. 



Cyathocrinus planus. — Mant. Wond. of GeoL 3rd. Ed. PL 119. 

 Formation and Locality. 



Altered beds of the mountain limestone. — Clevedon Ba}^ Somersetshire. 



The column of this species near the summit, is composed of alternate thicker and 

 thinner joints, which gradually become changed into joints of equal thickness. The 

 columnar canal is obscurely pentagonal, but owing to abrasion or some other cause, the 

 specimen from which figure 3 a, PI. 11, is taken, does not distinctly show the true form 

 of the column. This specimen has a body only three eights of an inch in diameter, and 

 a quarter of an inch in height. The rays are three inches in length, or twelve times as 

 long as the height of the body, and eight times as much as its diameter, so that when the 

 rays were spread out to their full extent, the circle formed by them was upwards of six 



