60 platycrinid^. — hexacrinus. 



Formation axd Localities. 

 Devonian strata — South Devon, Newton, and Plymouth. 



The plates of this species are very closely fitted to each other, and the non-ray- 

 bearing plate differs considerably in shape from the typical species. The meso plates 

 between the rays, bend abruptly over the abdominal cup, and with the abdominal plates 

 form a depressed covering to the vertex. 



This species attained to a considerable size, and is even larger than the first species. 



3. Species. Hexacrinus macrotatus. (Austin.) 

 PL VI. fg. 3, a, h, c, d. 



Definition — Dorso-central plate tripartite ; perisomic plates six, and elongated ; 

 abdominal plates, number of rays and column unknown. 



Si'NONYMES and REFERENCES. 



Platycrinus tuberculatus. — Phill. Supp. Pal. Foss. t. 60, Jig. 39*. 



Formation and Localities. 

 Devonian s^^stem. — South Devon, Newton, and Plymouth. 



Mr. Austen's specimens, from which our figures of this and the two preceding species 

 are taken, so clearly exhibit the arrangement of the plates, that it is quite improbable 

 that any Platycrinus, a genus to which all these specimens have been heretofore referred, 

 will ever be found with a divided hexagonal dorso-central plate, or with six perisomic 

 plates around the body. 



