POTEEIOCEINIDiE-POTERIOCRINUS. 83 



Formations and Localities. 



The Mountain limestone, Mendip Hills, Somersetshire. 



The P. latifrons is a very minute species the body scarcely ever exceeding the size of 

 half a pea J but although the body is so exceedingly small, the rays are comparatively 

 large and long. The primary or main rays are each composed of a single elongated 

 cuneiform joint ; on the outer slopes of these joints are two longer but thinner rays 

 composed of several joints, generally from eight to tenj the rays again subdivide making 

 the total divisional rays amount to twenty. 



The rays in this species are proportionately thicker than in the P. tenuis. 



This new species is extremely rare, and no scientific record with which we are 

 acquainted has noticed its existence. Its occurrence as far as our observations extend 

 is limited to the Mendips. 



10. Species. Poteriocrinus tenuis. (Miller.) 

 PL IQ.fig. 5, a, 5, h. 



Definition. — Body attenuated; mouth proboscidiform and centrical; main rays five, 

 each composed of a single elongated joint, and articulating by the whole width of the 

 narrow ray bearing plate; two thinner rays proceed from the sloping angles of the main 

 rays, making the total number of divisions ten ; column long. 



Synonymes and References. 



Poteriocrinus tenuis. — Mill. N. Hist. Crin.p. 71. 



Schloth. t. 2b. Jig. 3. 

 A new and peculiar species of Encrinus. — Cumb. Tram. Geol. Soc. Vol. 5. PI. 23.J. 1. 



p. 380. 1st. series. 



