171 Cephalopoda [Siphonopoda). 299 



Ammonites, and so, by analogy, on to Nautilus ; the induction 

 was blindly followed in a leader by " Naturforscher " (9), 

 At the beginning of this year Dr. v. Lendenfeld tried to convict 

 Riefstahl of similar blindness, and himself falls into the ditch 

 (12). With the drift, however, of his " Bemerkung " I 

 am glad to agree, since it is a repetition, though incomplete, 

 of two lines previously written by me. As the note con- 

 taining those lines (10) gives both abstract and criticisms of 

 Riefstahl's results, I beg my kind readers to glance at it 

 before continuing their present perusal. 



In this paper I wish : — I. to make a personal explanation 

 respecting the parallelism of v. Lendenfeld's work with mine; 

 II. to criticize his methods of work and argument; III. to 

 refute Riefstahl's conclusions ; IV. to propound a theory of 

 shell-growth that shall harmonize with the facts of phylogeny 

 no less than with those of ontogeny. 



I. Personal Statement. 



Von Lendenfeld says that Moseley was the first English 

 biologist to observe Riefstahl's paper, and that he consulted 

 Lankester, with whom v. Lendenfeld then was. My introduc- 

 tion to the subject also came from Prof. Moseley, who allowed 

 me to study it in his laboratory at Oxford ; and there my 

 work was done in the spring of 1887. Moseley at first in- 

 clined to Riefstahl's conclusions ; unhappily his sad illness 

 prevented subsequent discussion. The young Nautilus-shell 

 examined by v. Lendenfeld was seen by me at the British 

 Museum for the first time in July 1887 ; it of course confirmed 

 my previous conclusions. I never knew that anyone intended 

 to figure it. The editors of the Geol. Mag. had ray MS. by 

 the end of July 1887, about which time I heard that v. Len- 

 denfeld had been working on this point. The latter had, I 

 believe, left England when my note appeared, so that he 

 probably did not see it ; and I must apologize to him for 

 being delayed by ignorance of his address in sending him a 

 copy. _ 



This explanation was needed to show that, though v. Len- 

 denfeld and myself received inspiration from the same source, 

 our work was independent; it will also be seen that our 

 methods of work were not quite the same. 



II. Criticism of v. Lendenfeld. 



In the first place, it appears that v. Lendenfeld only ex- 

 amined a single young Nautilus-shell ; he, however, speaks 



