4 2 "J 



Frederick Chapman 



L. maccoyi 



L. tenisoni 



specifically distinct from the recent L. tenisoni in the following 

 particulars :- — 



Outline. Ornament. Iiental Armature 



Long ovate, very Radial stronger than Teeth short, 



oblique in ger- concenti-ic, the latter curved, com- 



ontio stage. being wavy and fimbri- paratively 



ate. few. 



Roundly ovate. Radial ornament strong, Teeth longer, 



oblique in ger- some undulose ; inter- more numer- 



ontic stage. spaces occupied by fine, ous. 



closely set bars, not so 



wavy as in L. maccoyi. 



Ligament pit in the fossil species usually smaller. 



The description of this form by McCoy, under the name of 

 L. helcheri (loc. supra cit.) is so full and precise as to obviate 

 any further reference to its specific characters here. It may, 

 however, be remarked in passing, that specimens in the neanic 

 stage usually show a crenulated inner margin, as in the northern 

 form, L. aurita ; but this character is lost in the later develop- 

 ment of the shell. 



This fossil form appears to be the progenitor of the living 

 species, as shown by its shape, and also by the general type 

 of ornament, which in L. tenisoni is less redundant, the fimbria- 

 tion being reduced to beads on the riblets, and to curved bars 

 in the interspaces. 



The differences between the Balcombian forms^ and the living 

 are so marked as to warrant a new name, and hence the shell 

 termed L. helcheri by McCoy, and later confused by various 

 authorities with some other tertiary shells of the same genus, 

 is here re-named L. maccoyi in honour of its first describer. 



Both L. rnorningtonensis, as before stated, and L. multi- 

 racliafa, are somewhat related in outline, the latter being prin- 

 cipally distinguished by its interrupted and bifurcated ribs. 



Dist?-ibution. — Balcombian. — Balcombe's Bay and Grice's 

 Creek, Port Phillip ; Gellibrand River, three miles W. of mouth 

 (G.S.V.). 



Janjukian. — ^Bird Rock Cliffs near Torquay (G.S.V.), very 

 rare. 



1 The Kaliniiian forms are smaller and are probably aniiectant with the recent species 

 This is borne out by the intermediate character of the surface ornament. 



