BY H. L. KESTEVEN. 69 



Veliger will reveal the fact that the sinuation of the outer lip 

 is referable entirely to mechanical factors, and that the weight 

 of the calcareous shell is to a large extent responsible ; such 

 sinuations do not occur in horny Nectoconchs. 



A failure to realise the fact that these variations are not of 

 phylogenetic signifiance has resulted in errors on the part of 

 the taxonomist. I was myself responsible for Mr. Hedley's 

 description of immature Cornlliophila Uschkeana Dunker, 

 under the name of I'ltrpura Kertata (17), on the evidence of 

 the Sinusigera apex, an error which his more recent discovery 

 of the adult shell from nearly the same locality has enabled 

 him to correct (18). Similarly believing that the size of the 

 symmetrical thimble-shaped nucleus of the protoconch {cali- 

 culus) was of phylogenetic significance, Dall used it for taxo- 

 nomic purposes when he advocated the retention of Coss- 

 mann's genus Austrotriton, although, as noted above, he was 

 apparently satisfied that, as judged by adult characters, the 

 type of the genus was rightly placed with forms developed 

 from smaller eggs, and, therefore, possessing the normal sym- 

 metrically coiled protoconch of the genus Cymatium. 



Of the disproportionately large apex discussed above, 

 three varieties are recognisable, the first or Mamillate is 

 typified in Scaphella mnmilla Gray, and gives its name to the 

 species ; the second or Eccentric is typified in Megalatractu? 

 aruanns Linn., and Cymatium looodsi Tate; the third or 

 Tumid apex is typified in Terehra laiirefano' Ten. Woods, 

 and Syrnola macrocephala Hedley, and is responsible for the 

 specific name of the last. In the first and second types, the 

 characters are in the caliculus, in the third type rapid growth 

 throughout the Veliger stages produces a large symmetrical 

 N ectoconch of two or more whorls. It has already been sug- 

 gestea that this rapid growth is due to the presence of a large 

 amount of nutritive material within the egg-capsule. This 

 suggestion is supported by the fact that, in those cases which 

 I have been able to study directly, as in those of which I find 

 information in literature, the whole of the larval stages are 



