vi INTRODUCTORY 
the third volume of Bronn’s ‘ Klassen und Ordnungen des Thier-reiches,’ pp. 8 and 9. 
Tt will be sufficient here to refer to this valuable publication, and to restrict our 
own remarks to one or two arrangements proposed subsequently to that publication. 
Dr. Mérch in a paper* ‘On the systematic value of the organs .. . in the 
classification of the Mollusca’ arrives at the conclusion, that the locomotive, res- 
piratory and other organs, which had been previously—by Lamarck, Cuvier, Blain- 
ville,+ and others—used as the leading principles in classification, do not really 
possess the value attributed to them; but that this is to be found in the ‘heart’ and 
the ‘generative organs.’ The author consequently divides the Mollusca (from which, 
strangely enough, he excludes the Bryozoa, BRAcHiopopA and others) into two 
series, MoNnoTo-caARDIA and Droto-cArpia. Each of these is further 
separated into two classes, namely, Androgynaand Exophallia on the one, 
Pseudophallia and Acephala on the other hand. The air breathing 
Univalves are considered of all the Mollusca the highest, and the monomyarian 
Bivalves the lowest in organization. As an instance, we may refer to the 
CEPHALOPODA, which are represented as being a little degree higher in organiza- 
tion than the Prnecyropa, forming with the Dzvrazips, the PoLyPLAcoPHoRA, 
CYCLOBRANCHIATA, part of the ScuTiBrancuiATA, Helicina and others, the class 
Pseudophallia. In fact such heterogeneous forms are brought together in this 
newly proposed classification, that no practical success seems likely to follow from 
its adoption, although several good hints regarding the development of certain 
forms from others appear to be contained in it. 
Very instructive information is embodied in another paper on the classification 
of Mollusca based on the principle of cephalization by E. S. Morse.{ The plan, upon 
which the Mollusca are organized, is stated to consist principally in the form of the 
fleshy sac containing the viscera and stomach. Mr. A. Hyatt consequently proposes 
to replace the name ‘ Moxtusca or Moutuscozoa,’ by the more appropriate one, 
SacCATA, equivalent to, and corresponding with, the names VERTEBRATA, 
ARTICULATA, and others. The morphological researches of Mr. Morse are 
quite in accordance with the generally accepted classification of the Mollusca, 
namely, into Bryozoa (Crnropopas), Bracutoropa, Tunicata (TUNIcoPopDA||), 
* Ann. Mage. Nat. Hist., London, 1865, 3rd Ser., Vol. XVI, p. 385. 
+ Vide Principes de Zooclassie, ou class. d. animaux, Paris, 1863 (Posthumous). 
t Amer. Jour. Sc. and Arts, 1866, 2d. Ser., Vol. XLII, No. 124, p. 19. 
§ 
We propose this name with reference to the cilia, or tentacles, surrounding the aperture. 
|| Proposed, with reference to the entire mantle serving, by its muscular action, or through its different appendages, 
as a locomotive organ. 
