424 Mr. F. A. Bather on Prof. Blake and 



(ii.) Ammonoidea, Cephalopoda in which the protoconch is 

 preserved by shell-coiling and comes to be affected thereby ; 

 (iii.) COLEOIDEA, Cephalopoda in which the protoconch is 

 typically preserved by an external sheath deposited by the 

 mantle ; the shell comes to be enveloped by the mantle, and 

 may partly, even wholly, disappear. The name Coleoidea 

 (/coXeo?, sheath) is congruous with the other two already 

 in use. 



The main points, then, have the very welcome support of 

 Prof. Blake ; there are, however, two which he has severely 

 criticized : — (i.) the suggestion that the membranes of the 

 septa are typically continuous with those of the shell- wall ; 

 (ii.) the theoretical assumption that the lamellge of Sepia are 

 homologous with the septa of a Belemnite-phragmocone. 



(i.) A supposition on which no argument is based may well 

 be described as " imaginary." But Prof. Blake's manner of 

 controverting the hypothesis is open to much objection. He 

 writes (' Annals,' p. 377), " if Mr. Bather had availed himself 

 of my observations of the shell of Nautilus .... he could 

 not have written as he does." Then follow two paragraphs 

 which distinctly profess to be an abstract of p. 17 et seq. of 

 Prof. Blake's Monograph. Whether the statements of Prof. 

 Blake in the ' Annals ' are in accordance with fact I do not 

 for the moment inquire ; it is enough to show that they do 

 not harmonize with the statements of Prof. Blake in the 

 Monograph. Prof. Blake {' Annals ') states that the out- 

 cropping edges of the fine laminse are 20,000 to the inch : 

 this statement is not in the Monograph ; on the contrary, 

 from pi. ii. fig. 8 of that work it appears that Prof. Blake's 

 '' outcropping edges " are 4000 to the inch, 2800 in fig. 7, 

 while in the earlier chambers they can be " seen under a low 

 power," and are drawn in pi. ii. fig. 5 at about 450 to the inch. 

 The slight curvature of the shell cannot explain the discre- 

 pancy. Next, Prof. Blake (' Annals ') states that the obliquity 

 of these laminaj " is very slight, so that in tracing them from 

 their commencement inside to their termination against the 

 outer layer of the shell, they pass more than one septum " : 

 this statement is not in the Monograph, nor can it be inferred 

 from the figures ; on the contrary, in pi. ii. fig. 1 oblique lines 

 are seen to pass from the inside to the outside within the space 

 between two septa. Lastly, Prof. Blake (' Annals ') states 

 that the shell is composed of three layers, and that " the third 

 layer is a thin amorphous substance covering the whole of the 

 interior of the shell ... In the later portion of the shell . . . 

 it is seen between the septum and the shell, completely sepa- 



