312 Dr. T. Wright on neiv Species of Echinodermata 



ting muscular fascicles ; d, radiating imparietal blood-channels ; 

 d, setae. 



Fig. 10. Liver-folUcle of the Lobster, viewed by transmitted light : 

 a, b, caecal end, having glandulose walls by the swelling of the 

 parietal epithelial cells ; c, the secreted product in its first stage, 

 oil-cells colourless and minute ; d, d, the same increasing in size 

 and becoming yellow in colour ; g, oil- cell ; h, yellow cell. 



Fig. 11 i^fig. 12 enlarged. It shows the ultimate structure of the tentacle 

 of a Prawn. The muscular masses occupy the axis, and the blood- 

 corpuscles course along the sides. 



Fig. 13. Illustrates the mode in which the ultimate nerve-tubules are dis- 

 tributed in the gill-laminae of several Crustacea : h, c, nerve- 

 tubules ; e, patches of parenchyma. 



[To be continued.] 



XXIX. — Contributions to the Paleontology of Gloucestershire: — A 

 description, with Figures, of some new Species of Echinodermata 

 from the Lias and Oolites, By Thomas Wright, M.D. &c., 

 Professor of the Natural Sciences in the Cheltenham Grammar 

 School*. 



[With three Plates.] 



[Continued from p. 173.] 



Genus Pedina, Agassiz. 



As this genus was incorrectly defined in our memoir on the 

 Cidaridse, it having been there stated that the mammillary emi- 

 nences were ^' crenulated like those of Diadema," we take this 

 opportunity of correcting the error, and giving a definition more 

 in accordance with our present knowledge. 



Test thin, circular, more or less depressed ; primary tubercles 

 small and perforated ; mammillary eminences with smooth ring- 

 like summits without crenulations ; pores in general disposed in 

 triple oblique pairs ; mouth small and slightly decagonal, mar- 

 gin not much notched; ovarial disc small and not prominent; 

 ambulacral areas with one, two, or more rows of small tuber- 

 cles ; interambulacral areas sometimes with two rows only, some- 

 times with two rows and additional secondary rows of tubercles 

 more or less complete. 



This genus is extinct, and is found in the oolitic cretaceous 

 rocks. 



Pedina Bakeri, Wright. PI. XI. fig. 4, a-c. 



Test circular, depressed ; ambulacral areas narrow^ with one row 

 of small tubercles disposed in a slightly zigzag line down the 

 centre of the areas ; interambulacral areas broad, with two rows 

 of primary tubercles raised on prominent mammillary emi- 



