49 



THE CONSTITUTION OF THE GASTROPOD PROTO- 

 CONCH: ITS VALUE AS A TAXONOMIC FEATURE 

 AND THE SIGNIFICANCE OF SOME OF ITS 

 FORMS.* 



By H. LaiGHTON Kkstkven, D.Sc, Lecturer in Physiology 

 AND Biochemistry, Technical College, Sydney. 



(Communicated hy Dr. H. G. Chapman.) 



(Plate i.) 



Introduction. 



In August, 1905, I read, before this Society, a paper on 

 "The Onotogenetic Stages represented by the Gastropod Pro- 

 toconch" (30). The more important portion of this papei 

 had been forwarded to the editors of the Quarterly Journal of 

 Microsco'plnd Science about six months previously, and was 

 published in that journal in October of the same year (32). 



Since penning those papers — which were themselves the 

 outcome of over four years' stud}'^ of the Gastropod Proto- 

 conch, as represented in a collection, such as falls to the good 

 fortune of but few to study — I have subjected the tlieories 

 and opinions therein put forward to thoughtful criticism 

 from time to time, and have collected further notes on the 

 subject. Our knowledge of the Protoconch has also been 

 enriched in the interval by many contributors, taxonomists 

 describing new species, and my own contributions have 

 aroused criticism, favourable and otherwise. These contri- 

 butions, and my own recent studies in comparative Zoo- 

 logy and Physiology, permit me to review the subject from a 

 broader standpoint, and at the same time to treat some of 

 its aspects in more detail. Meanwhile, during the five years 

 which I have devoted to these other subjects, I have to a cer- 

 tain extent lost touch with general Malacology, and must on 



*Submitted as a Thesis for the degree of D.Sc, to the Faculty of Science 

 of the University of Sydney, in 19U. 



