141 



the shoulder defined by a thick spiral rib, ornamented by very 

 thick, ang'iilarly rounded, straight ribs (about 15 on the penulti- 

 mate whorl), separated by very much narrower interspaces. 

 Aperture oval-oblong, squarely rounded behind, abruptly con- 

 tracted to a somewhat short and slender beak. Outer lip thin, 

 smooth within ; columella Avith three or four plaits. 



Dimensions. — Length, 5-5; breadth, 1-75; length of aperture, 2. 



Locality. — Lower beds at Muddy Creek. 



15. Mitra paucicostata, spec. nov. Plate v., fig. 2. 



Shell turriculate, ending in a relatively large pullus of two- 

 smooth convex turns, the top laterally immersed. 



Whorls four and a half, excluding pullus, medially subangu- 

 lated, ornamented with slightly bent angular cost^e, which are 

 subtuberculated on the spiral keel and at each suture (15 on 

 penultimate whorl) ; interspaces faintly striated transversely. 



Last whorl oblong, abruptly attenuated to a short, broad, re- 

 verted beak, which is spirally ridged; flatly rounded at the 

 suture, ornamented with acute cost^e, a slightly tuberculate 

 antesutural keel, and two approximate tubercular ridges in an 

 alignment with posterior angle of the aperture. Outer lip thin, 

 roundly insinuated at the suture ; internally lirate ; columella 

 with four stout approximate plaits. 



Dimensions. — Length, 8-5 ; breadth, 4-5 ; length of aperture, 4. 



Localities. ~~LlQ>\\^v beds at Muddy Creek ; blue clays at 

 Schnapper Point. 



16. Mitra terebreeformis, spec. nov. Plate v., fig. 5. 



Shell fusiformly elongate, smooth, shining, ending in a stout 

 high pullus of two turns, the first very small. Whorls six and a 

 half, excluding pullus, nearly flat, ornamented by much curved 

 angular plications, separated by very much broader shallow de- 

 pressions ; the posterior suture margined by a narrow band, de- 

 fined by a thread-like keel. 



Last whorl gradually attenuated into a short, broad, upturned 

 beak, the curved costas becoming obsolete in front of the middle- 

 line ; the beak is spirally ridged. 



Aperture ovate, angular behind ; outer lip thin, smooth 

 within ; columella with four approximate plaits. 



Dimensions. — ^Length, 16 ; breadth, 5 ; length of ajDerture, 7. 



Locality. — ^Upper beds at Muddy Creek. 



The shape, the curved costse, and the antesutural band recall 

 some of the leading characteristics of Terehra, and separate this ■ 

 species from all others of the genus, recent and fossil. 



