81 



Form, and Loc. — Eocene : Muddy Creek, Victoria. 



G. 5511. An adult specimen, longitudinal costiB distantly 



separated. Purchased. 



G. 9335. Two examples, one of whicli illustrates the senile 



stage. Purchased. 



Harpa (Eocithara) abbreviata, Tate. 



1889. Sarpa abbreviata, Tate, Trans. Eoy. Soc. South Aust. vol. xi. p. 150, 

 pi. vi. fig. 7. 



Protoconeh (Plate IV. Figs. 5a-h) composed of two turns ; it 

 has the general features of that of H. tenuis, but differs in that 

 the initial portion is much inflated and is sharply defined from 

 the remainder. The anterior portion of the turns may be divided 

 into two parts, the earlier of which (like the first turn) is smooth, 

 and the later is obscurely ribbed. The last-mentioned character is 

 of much value in working out the phylogeny of the Gasteropoda ; 

 the more pronounced generic characters were imparted to the shell 

 whilst yet in the embryonic stage, prior to the escape of the 

 animal from the capsule. In the brephic stage the incised suture 

 is initially accompanied by an elevated border, which becomes 

 modified as the animal approaches the neanic stage, and altogether 

 disappears in the adult. The shell in the brephic stage also 

 has some rather bold spiral elevations on the whorl, which, in 

 conjunction with the closely-set longitudinal ribs, cause cancella- 

 tion, but this is wanting in the adult form. 



A cursory examination might lead one to think that this species 

 was merely a variation of H. tenuis, with which it could not 

 possibly be confounded, however, when the protoconeh and shell 

 in the brephic stage are compared. The ordinary spire-whorls are 

 subangulated medially, and ornamented by rather distant, slightly 

 elevated lamellae. 



Dimensions. — Length 24 mm.; breadth 14-5 mm. ; length of 

 aperture 18-5 mm. 



Form, and Loc. — Eocene : Muddy Creek, Victoria. 



G. 4216. Two specimens. Presented hy John Pennant, Esq. 



