280 Mr. T. Austin on the Connexion between 



the ambulacra!, and like them set distinct from each other, which 

 gives the surface of the test a nodulated air ; a slight furrow passes 

 down the centre of the interambulacral arese, dividing them into 

 two parts ; the rows of tubercles diminish in number at the apex 

 and base of the arese, they are larger and more fully developed, 

 however, in the latter region; the apical disc is small, ring- 

 formed, and prominent; the poriferous avenues are deep and 

 strongly defined, the pores are arranged in simple pairs above, 

 but they form double ranges which fill up the wide space at the 

 basis of the arese ; the base is concave, the mouth is large and 

 pentagonal like the former species, the notches are closely ap- 

 proximated at the bases of the interambulacra, and the marginal 

 arch over the ambulacra is straight and wide ; the tubercles dis- 

 posed at the bases of both arese are larger and more fully developed 

 than those occupying the sides. 



Affinities and differences. — The size of the tubercles and their 

 diminished numbers when compared with A. Forbesii serve as a 

 sufficient diagnosis whei'eby A. nodulosa may be distinguished 

 from the former Urchin; the slight median furrow down the centre 

 of the interambulacral arese is very different from the deep line se- 

 parating the arese mA. Forbesii into two equal nearly conical lobes. 



Locality and stratigraphical range. — This species was collected 

 by my friend the Rev. P. B, Brodie from the bed of clay resting 

 on the Stonesficld slate at Sevenhampton Common, along with 

 Acrosalenia spinosa and Pecten varians ; this bed occupies the same 

 relative position in other parts of Gloucestershire, and is probably 

 the basal clay band on which the shelly freestone beds of the 

 Great Oolite rest. I only know the solitary specimen before 

 me; in Germany, Count Miinster found it in the Jurakalk of 

 Baireuth. 



History. — First figured and described as an Echintcs by Gold- 

 fuss. I am not aware of its having been noticed before as a 

 British fossil. 



My thanks are especially due to Mr. W. H. Baily for the pains 

 he has taken with the beautiful figures which accompany this 

 paper, the original specimens of which are in my cabinet. 



XXII. — Observations on the Connexion between the Crinoidese and 

 the Echinodermata generally. By Thomas Austin, F.G.S., 

 Fort Major, &c. 



In offering these observations and generalizations relative to the 

 Crinoidese, it is but an act of justice to acknowledge how deeply 

 we are indebted to the laborious researches of those who have 

 preceded us in this branch of inquiry. Among the writers on 

 the Crinoidese who have thrown considerable light on this im- 



