TWO SPECIES OF ASTRALIUM FROM PORT JACKSON, 



Astralium tentoriforme,Tvyoi\,^l?ii\. Conch, x., p. 240, pi. 53, figs. 



41,42, 1888. 

 Trochus ^fimhriaW.s, Quoy k Gaimard, oj). cit., pi. 61, fig. 9, 1835. 



A, tentorifornie. 

 Fig. 2. — Neanic stage. 



Quoy lV: Gaimard {Joe. cit.) speak of a variety "plus epaisse et 

 plus pyramidale " which w^as evidently the original of their fig. 9. 

 Philippi quotes this figure as being of his T. urvillei. Fischer 

 regards Philippics sjDecies as the young of a variety /3, 7\ georgianus, 

 being presumably the adult; the figure of this is the best represen- 

 tation of A. tentoriforme as it is known in Port Jackson. The 

 species is ^ery common in all the fresher reaches of Sydney 

 Harbour and the coasts of New South Wales. 



In literature these two species are more distinct than in life. 

 Both species are very variable. Specimens of A. tentoriforme 

 occur nearly as flat as A. Jimhr latum, var. squamiferum, and 

 almost as fimbriated as var. cucidlatiim (see Tryon's figs. 52, 50) 

 whilst pyramidal unornamented specimens of A. Jimhriatum. Si,ve 

 not uncommon. M}'- figures show the differences between these 

 species in their neanic stage. The best characters for identifica- 

 tion of the adult shells are offered b}^ the base, and may be 

 tabulated as follows : — 

 A. fimhriatum. 



(1) Base convex. 



(2) Columella ending in a 



small tooth 



(3) Lower lip joining the 



upper lip at the extreme 

 edge. 



A. tentoriforme 



(1) Base concave. 



(2) Columella ending in a pro- 



minent tooth. 



(3) Lower lip .set inside the 



upper lip 



