rt 



192 



emmulated ribs of about equal magnitude, at the suture there 

 is a double smaller rib, and there is a finer one posterior to the 

 periphery. The transverse riblets of the penultimate whorl with 

 increasing revolution of the whorls become more slender and 

 closer together, and thus the fenestrated ornament is somewhat 

 obscured on the front part of the body-whorl. Below the peri- 

 phery there are about live revolving equal-sized ribs, more or less 

 gemmulated at the intersections of transverse sigmoidal threads, 

 the one margining the umbilicus most conspicuously so. The 

 umbilical wall has about live flat threads crossed by lamella-like 

 stride. 



Dimensions. — Height, 1-75; basal diameters, 4'25 ; and 5 

 (vix) ; major diameter of umbilicus, 2 '5 (vix). 



Localities. — Three dead shells, Aldinga Bay and Semaphore. 



Affinity.— The conspicuous oblique ribbing and very wide 

 umbilicus are characters which separate this species from the 

 majority of its congeners. Its near allies are T. aspera and 

 T. fenestrata, but it is flatter than the former, and more angu- 

 lated than the latter ; unacquainted with either, except by 

 Tryon's figures and descriptions, a critical comparison is not 

 possible. 



Turbo (Astralium) rutidoloma,* spec. nov. PL i., fig. 9. 



Shell lenticular-conoid, about equally sloping above and below 

 from the angular periphery; whorls four and a-half, flat, the 

 embryonic one and a-half whorls fimbriated at the suture; 

 umbilicus minute. Operculum as in T. aureus. 



Upper-surface of body-whorl with a stout and a broad lira 

 next the suture, which is transversely crenulate-ridged ; peri- 

 phery bluntly angled by a slightly compressed convex keel, 

 which is obsoletely crenulated ; between the keel and the sutural 

 band are three granulose lirte about equidistant and equal-sized 

 but the anterior one is close to the keel (in senile specimens a 

 small lira is interposed next the suture, and there is a tendency 

 in the granules of the lirae to become somewhat confluent); the 

 intervals between the liras are smooth. The base has four 

 granulose line ; the umbilical region is bounded by a broad ridge, 

 which is broken-up into claviform tubercles obliquely disposed. 



Colour greenish-brown in living specimens, flesh-coloured with 

 rufous lirse and darker-tinted at the suture and keel in beach- 

 examples. The interior of the aperture of living examples is 

 greenish and of a pearly lustre. 



Diinensio7is. — Height, 7'5 ; basal diameters, 10*5 and 12. 



Localities. — At low tides, Moonta Bay (Messrs. Mauglian and 

 McDougall): in eight fathoms, Hardwicke Bay (Dr. VercoJ. 



* In allusion to the.wrmkled border at the anterior suture. 



