FROM THE GREY CHALK AND FARRINGDON BEDS. 69 



all other forms at present known that they cannot be mistaken for any other species, the 

 long smooth lower portion of the stem forming such a conspicuous specific character of 

 this spine. 



Stratigrapldcal Position. — The specimens I have figured were collected from the 

 Sponge-gravel nearFarringdon, in Berkshire, associated viii]! Pscudodiadema rotulare, Ag., 

 Hyposalenia Wri^Idii, Desor, Hyposalenia Lardyi, Desor, Salenia areolata, Wahlb., and 

 two new species of EcJiinobrissus, together with the Amorphozoa and Mollusca that 

 characterise this remarkable formation. 



My kind friend the Rev. T. Wiltshire, F.G.S., at my request, has contributed the 

 following additional notes on some rare tests and spines of Cidares in his collection. 

 These are figiu'cd in Pis. XH and XHI. 



" In the course of last year you expressed the desire that I should send you some 

 notes in reference to the fossils figured in Plates XH and XHI of your Monograph on 

 the Cretaceous Echinodermata. In compliance, therefore, with your wish, the following 

 remarks are forwarded, to be used or rejected as may seem most fitting. 



" The Urchin drawn in figure 1 , Plate XII, is probably a new species intermediate 

 between Cidaris sceptrifera and C. subvesicnlosa . I would suggest it should be named 

 C. intermedia ; it may be thus defined : — 



Cidaris intermedia, Wiltshire. PI. XII, figs. 1 a, 1 1. 



"Test moderately large, inflated; ambulacral areas narrow, depressed, flexuous, with 

 six rows of granules in the middle, the outer two the largest, diminishing to four rows 

 above and below ; poriferous zones winding, narrow, depressed, at the ambitus about the 

 same width as the semi-ambulacral areas, narrower above, wider below ; interambulacral 

 areas wide, plates large, five in a column ; areolas proximate, deep, suboval, with an 

 elevated slightly overhanging scrobicular margin, encircled by a series of small granules, 

 equal in dimensions to those of the outer row of the ambulacral areas, bosses not prominent, 

 summit smooth, tubercle moderate in size, perforated; proximal discal plate in each 

 column with a rudimentary tubercle, in a circular area ; miliary zone narrow, filled with 

 small equal-sized granules depressed along the line of sutures ; apical disc wide, of the same 

 diameter as the peristome ; ovarial plates thick ; jaws stout, triangular ; spines long, slender, 

 cylindrical, slightly tapering, surface marked by regular longitudinal rows of spiny 

 projecting granules, the intervening space finely shagreened. 



" Dimensions. — Height ^'^ths of an inch (the specimen being very slightly crushed) ; 

 transverse diameter 1 inch and /^ths. 



" Description . — The test of this Urchin is circular, and is equally depressed at both 



