213 



" The enormously extended circular thin flange into which the 

 base is extended renders this cowry totally unlike any previously 

 known living or fossil species. Length and width of body -whorl 

 2|- and 2 inches ; with disc length and width 4^ inches. Spire 

 small, blunt, of two volutions. Rather rare at Mornington, 

 Hobson's Bay." — McCoy. 



Genus Trivia. 



synopsis of species. 

 Shell cross-ribbed. 



Shell globose, with linear dorsal furrow. 



1. T. acellanoides. 

 Shell oblong, with large dorsal smooth area. 



2. T. erugata. 

 Shell smooth, without cross-ribs, globose. 3. T. pompliolugota. 



1. Trivia avellanoides, McCoy. 



1876. Cypra3a (Trivia) avellanoides, McCoy., Pal. Vict., Decade 



III., tabs. 28, 29, figs. 3— 3c. 



1877. Trivia Europsea (Montfort), Tenison- Woods, Proc. Ptoy. 



Soc, Tasmania, p. 91. 

 1879. Trivia minima, Tenisoii-Woods, Proc. Lin. Soc, N.S. Wales, 



vol. I v., p. 4, tab. 1, tig. 8. 

 1884. Trivia avellanoides (McCoy), Tate, Vvoc. Roy. Soc, Tasm., 



p. 209 ; id., Johnston, p. 222. 



Shell thin, oval-globose ; surface ornamented with very narrow, 

 sharply defined, thread-like ridges, which are usually interrupted 

 by a narrow smooth space along the middle line of the back. 



As pointed out by McCoy, it is much more globose and has 

 much fewer and more distant cross-ribs than T. australis ; but it 

 is the counterpart of T. avellana, Sow., of the English Crags 

 (hence its specific name), distinguishable especially by its uni- 

 formly shorter and more spheroidal form. 



Tenison-Woods referred dwarfed examples of this sjDecies to 

 T. EuropcHct, from which it is separable by much the same char- 

 acters as it is from T. austrcdis. 



Tenison-Woods figures and describes an early stage of growth 

 of this species as T. minima, relying for a differential character 

 on the absence of a dorsal division between the ridges ; he judged, 

 moreover, the shell to be an adult because of the thickened lips, 

 overlooking the fact that Trivia, unlike Cypra^a, exhibits no shell- 

 metamorphosis. An examination of many small examples of 

 T. avellanoides permits me to state that the smootli dorsal area 

 does not begin to develop until the shell has reached a length of 

 about eight millimetres. 



Dvniensio7is. — Length of a large specimen, 31 ; the average 



