FROM THE UPPER GREENSAND. 173 



Salenid^e. The test is depressed on the upper and under surfaces, and the sides are 

 inflated between. The poriferous zones are narrow, and the pores unigeminal throughout. 

 The ambulacral areas are straight and narrow, with twelve pairs of marginal, close-set, 

 homogeneous granules, and a few granulations between them at the widest part thereof 

 (fig. 1 d). The inter-ambulacral areas are wide, and filled with two rows of large tubercles, 

 four in each row ; those in the upper part of the area are the largest, and they gradually 

 diminish in size from above downwards ; the bosses of the tubercles are very prominent, and 

 their summits sharply crenulated ; the mammillon likewise is large (fig. 1 d). Two rows of 

 large granules occupy the miliary zone, and describe a zig-zag ornamentation on each side 

 of the mesial suture, and two granules occupy the angles of each of the plates at their zonal 

 side, so that the test of this small species has a highly ornamented appearance (fig. 1 c,d). 



The apical disc is large, solid, and remarkable for the absence from its ovarial plates of 

 sutural lines or punctuations ; its border is thickened, and recurved, and near this marginal 

 bourrelet are ten wide equidistant punctures (fig. 1 a) ; the vent is round, the periprocte 

 annulated, not much elevated, and slightly excentral (fig. 1 a, c). 



The mouth-opening is very large, one half the diameter of the test ; the peristome is 

 deeply incised, and the oral lobes are slightly unequal (fig. 1 b). 



Affinities and Differences. — Salenia Loriolii resembles Salenia minima in the closely 

 united sutures of its apical disc, but differs from it in the larger development of its tubercles 

 and wideness of its mouth-opening. It differs from Salenia Desori, associated with it in 

 the same " terrain" in which it is found, in possessing larger tubercles, a smooth disc without 

 punctuations, and a much larger mouth-opening. A comparison of the capital figures of 

 these two Salenice on the same plate places their affinities and differences better before the 

 student than any verbal description. 



Locality and Strati graphical Position. — This rare specimen belongs to the British 

 Museum, and was collected from the Upper Greensand near Warminster. 



I have dedicated this Urchin to my friend Monsieur P. de Loriol, of Geneva, one of 

 the learned authors of the ' Echinologie Helvetique,' and of several other important works 

 on the Geology and Palaeontology of Switzerland. 



Salenia Desori, Wright, nov. sp. PI. XXXV fig. 2 a—/. 



Diagnosis. — Test small, circular, depressed, upper surface convex; ambulacra straight, 

 narrow, with two rows of mammillated granules ; inter-ambulacra wide, four or five 

 moderate-sized tubercles in each row ; pores unigeminal throughout ; apical disc promi- 

 nent, with large punctuations along the sutural lines ; mouth-opening moderate ; peristome 

 deeply incised ; lobes nearly equal. 



Dimensions. — Latitude, four and a half lines ; altitude, two and a half lines. 



Description. — This pretty little Salenia was collected with & Loriolii in the Upper 



