the septation with great distinctness. Mr. Brady, to whom 

 specimens were submitted, informs me that he has occasionally 

 met with examples similar to the present in recent material 

 associated with S. crenata, Kar., and at the time regarded it as a 

 weak thin-shelled modification of that species. *S'. crenata does- 

 not occur in the Muddy Creek material, but the form now des- 

 cribed is comparatively common, and in no instance have I seen 

 the slightest tendency to crenulation of the test as in S. crenata^ 

 There is therefore no alternative but to assign it a specific posi- 

 tion. I have great pleasure in associating the name of my friend 

 Prof. Ralph Tate, F.G.S., with this shell, as one who has devoted 

 much time and conspicuous ability in working out the mollusca 

 of the beds from which the species now described has been ob- 

 tained. Lower Bed, moderately common. 



Genus — Corxuspira, Schultze. 



30. *C inroJvens, Rss. The larger examples exhibit an orna- 

 mentation of fine wavy disconnected stria:', running in a line with 

 the convolutions. Lower Bed, rather scarce. 



31. *C.folincea, Phil. It is worthy of note that all the speci- 

 mens, which are more or less weathered, show a fine surface orna- 

 mentation resembling C. striolafa, Brady ; but they undoubtedly 

 belong to the above species, and the ornamentation seems to ha^e 

 been brought out as an effect of weatliering. Lower Bed, rather 

 scarce. 



32. *(7. crassisepfa, Brady. Lower Bed, rare. 



Genus — Hauerixa, fTOrhiyny. 



33. fi/. intermedia, s^dcc. nov. PI. i., fig. 6. 



Test free, comj^ressed, consisting of two or three convolutions,, 

 which increase in size towards the oral extremity. Segments 

 compressed laterally, arcuate, inflated, from six to ten visible 

 externally and from three to five in final convolution ; segmenta- 

 tion marked externally by lines of sutural constrictions. Surface 

 of test, smooth ; colour an opaque-white. Peripheral margin 

 carinate, sub-carinate, or rounded. Aperture never compound, 

 but Milioline in character, formed by a slight constriction of the 

 chamber cavity, and furnished with a long straight tooth rising 

 from the inferior portion of the peripheral margin of the final 

 chamber, and extends to about half the diameter of the aperture 

 in a line with the medial plane. Adult specimens, -^^ in. 



The most striking feature of the form now described is tlie 

 divergence which it exhibits from the generic type in relation to 

 the aperture. Ilaiierina, as a rule, carries a very distinctive 

 cribiform or compound orifice, whilst the present species is con- 

 spicuously and (so far as my observation has gone) invariably 



