144 



23. Mitra cassida, spec. nov. Plate vi., fig. 5. 



Shell small, stout, biconic, witii a very short, somewhat acu- 

 minate spire, ending in a relatively large papillary pullus. Ordin- 

 ary spire whorls convex, ornamented with slender costa?. 



Last whorl ventricose posteriorly, al^ruptly sloping to the 

 suture, and rapidly attenuated to the front ; tlie shoulder of the 

 whorl ornamented with transverse sub-tuberculose ridges. 



Aperture narrow-elliptic ; outer lip thin, smooth ; columella 

 with four plaits. 



Dimensions. — Length, 7 ; breadth, 4 ; length of aperture, 5-5. 



Locality. — Upper beds at Muddy Creek. 



24. Mitra conoidalis, spec. nov. Plate x., figs. 2« — b. 



Shell small, stout, biconic, with a short regularly conic spire, 

 ending in a relatively large depressed pullus ; ordinary spire 

 whorls nearly flat, sloping more rapidly to the anterior suture, 

 and slightly margined at the posterior suture ; ornamented by 

 slender costee and a few spiral engraved lines. 



Last whorl oblong, rather abruptly attenuated at the base,, 

 flatly rounded over the suture ; with a few revolving threads at 

 the shoulder and at the base, the median portion transversel}'' 

 striate. 



Aperture narrow-elliptic ; outer lip thin, smooth ; columella 

 with four plaits. 



Dimensions. — Length, 7 ; breadth, 3-5 ; length of aperture, 5-5.. 



Locality. — Lower beds at Muddy Creek. 



FAMILY OLIVID.E. 

 Genus Oliva. 

 It is not possible to separate conchologically Olivella from 

 Oliva, as the only difference between them is the longer or 

 shorter spire, Avhich is by no means an absolute measure, though 

 it is not improbable that the following species may belong to the 

 former genus. 



SYNOPSIS OF SPECIES. 



Length more than three times the breadth. L 0. angustata. 

 Leng-th less than three times the breadth. 



Shell narrower ; spire longer. 2. 0. Adelaides. 



Shell wider : spire shorter. 3. 0. nymjyhalis. 



1. Oliva angustata, spec. nor. Plate viii., figs. Ja — d. 



Shell narrowly elongate-ovate, shining ; spire acuminate, of six 

 whorls ; suture excavated ; aperture narrow, longer than the 

 spire ; columella twisted with five or six anterior spiral grooves. 



Dimensions. — Length, 18-5; breadth, 5-5; length of aperture,. 



