217 



Strombus denticostatus, sp. nov. 



[Plate VI. Fig. 8.] 



Shell elongate ; whorls eight in number, those of the spire 

 longitudinally costate in the earlier stages, the costae there being 

 numerous, and extending almost from suture to suture ; in sub- 

 sequent stages these are modified, being much contracted, and 

 becoming dentate at the periphery ; on the body-whorl the costse 

 have shrunk, and are represented by immense, dentate, very 

 distant tubercles ; the other ornament of the spire consists 

 essentially of closely-set spiral lineations, which are broken up 

 into wavy undulations on the body-whorl of the adult by the 

 crossing of the lines of growth ; the outer margin is expanded and 

 wing-like, extending as a broad wide lobe posteriorly, rounded at 

 the extremity, and joining the spire at the posterior suture of the 

 penultimate whorl ; this aliform expansion tapers towards the 

 front by a graceful curve, the shell in that region becoming much 

 narrower in consequence ; the exterior aspect of the wing shows 

 that the spiral lineations become bolder and spi'ead out until they 

 attain the margin ; in particular, a bold keel fortifies the prolonged 

 lobe alluded to, whilst the growth-lines become prominent, almost 

 rugose ; anterior canal truncate. 



It is unfortunate that the only example of this ornate species 

 in the Museum collection is an impression in limestone of the 

 back of the shell ; but, as will be seen from the figure (Plate VI. 

 Fig. 8), which is drawn from a plaster cast, the impression is very 

 perfect, and it seemed desirable to place this distinctive species on 

 record. 



Dimensions. — Length 43 mm. ; breadth (including aliform ex- 

 pansion) 23 '5 mm. 



Form, and Loc. — Tertiary : Tallowan Well, Fowler's Bay 

 District, South Australia. 



G. 9654. Impression of the shell, apparently of the adult, in 

 a block of shelly limestone. U. Y. L. Brown Coll. 



