177 



Murex (Triplex) otwayensis, sp. nov. 



[Plate VI. Figs. 5a-d.] 



Shell small, narrow, spire elevated ; protoconch composed of 

 one and a half smooth turns, invaded by scalariform longitudinal 

 laraellfe, which appear to proceed from the brephic stage of 

 growth, crossing the suture and affixing themselves to the pre- 

 ceding turns of the protoconch; varices three to each whorl 

 in the neanic and ephebic stages, but more numerous on the 

 earlier whorls, foliated, crenulated on the edges due to the 

 prolongation of the spiral lineations, which are far apart, not 

 more than four or five being developed on the penultimate whorl ; 

 the anterior aspect of the variceal folia exhibit the usual undu- 

 lating scales of growth, whilst there is a prominent hollow spine 

 of medium length projecting from each folium, situated posteriorly, 

 in the neighbourhood of the suture ; the intervariceal longitudinal 

 costae are about six in number on the penultimate whorl, and 

 their intersection with the spiral lines cause tessellation of 

 a peculiar character, each point of junction being crowned by an 

 obtuse nodulatiou ; the anterior half of the body-whorl is compara- 

 tively denuded of ornament ; aperture quadrate, open anteriorly, 

 peristome continuous except at the entrance of the canal ; outer 

 margin slightly reflected ; canal short, almost covered up. 



This shell is more ornate than either of the preceding species 

 of Triplex, and forms a link between that subgenus and Chicoreus 

 through the medium of its variceal spines. The protoconch is 

 highly distinctive ; it is doubtful whether part of the scalariform 

 structure did not originate within the capsule, but the folia 

 being longitudinally continuous and unbroken from the brephic 

 Btage across the suture, the point cannot be definitely resolved 

 by the few specimens in the Museum collection. Compared with 

 M. contahulatus, Lamarck, of the Paris Easin, with which it 

 presents some analogy, the latter is found to possess more convex 

 whorls, is broader, larger, and is minus the intervariceal tessellation. 



Dimensions. — Length 11mm.; breadth (including spines) 5 mm.; 

 length of aperture 3'2o mm. ; length of canal 2'75 mm. 



Form, and Loc. — Eocene : Cape Otway, Victoria. 



G. 9457. Three examples of the adult. Purchased. 



N 



