74 POTERIOCRIMD^:. POTERIOCRINUS. 



crinoids have been found with univalves inclosed within their rays in such a position as to 

 leave but little doubt that a sudden death had overtaken them in the midst of their repast. 



Many species of Crinoidea, as some of the Actinocrini, with their long flexible narrow 

 pointed oral tubes most probably fed on the corals which abounded in the early seas of 

 our planet. In the proboscis of the Aclinocrinus pohjdactyliis, and some other species 

 we find an instrument well suited for searching among the coral branches, and extracting 

 the soft fleshy zoophytes from their calcareous cells. 



Miller's figure 1. page 68, and our figure PI. 8, 3 c,are drawn from the same specimen; 

 the difference in the figures may be accounted for by the fact that Miller attempted a 

 restoration, and we have endeavoured to convey a faithful portrait of the original. 

 This specimen is now in the museum of the Bristol Institution. 



2. Species. Poteriocrinus isacobus. {Austin.) 

 PL S,fig. 4 a, and b. 



Definition. — The dorso-central and perisomic plates, appear to agree in number with 

 the typical species. Primary and secondary rays are each composed of a single elongate 

 joint; minor digitations formed of several. 



Synonymes and References. 



Poteriocrinus minimus. — Austin, Ann. Nat. Hist. Vol. 10, p. 108. 

 isacobus. — Austin, Fo^. 11, p. 195. 



Formation and Localities. 



Mountain limestone. — Mendip hills ; Black Rock, Avon side, Bristol ; Hook Point, 

 Wexford. 



This diminutive species of Poteriocrinus is another example of the diversified struc- 

 tures amoEg crinoids of the ancient seas, for here we find the rays constructed differently 

 from those of all-other known species ; and while they convince us by their form, ihey were 

 less flexible than in any crinoid we have previously described, they assure us that the 



