30 MR. R. GARNER ON THE SHELL-BEARING MOLLUSCA. 



animals. He thinks that the idea of an ascending and successive 

 scale or chain of creation is, in the main, correct, when the great 

 classes, and not species or genera, are made the links, — the dis- 

 turbing or modifying influences being due to modes of life, food, 

 habitat, &c.,and causing a different (say the quinary) distribution. 

 He is an advocate, too, for the doctrine of one fundamental plan 

 of organization, and thinks that, in the zoophyte, there is a real 

 union of both the animal and vegetable nisus. 



The great divisions of this chain, the radiate, articulate, mollus- 

 cous, and vertebrate, constitute an ascending series ; the links of 

 the chain, so to speak, being in each case, for such an extent, of a 

 particular pattern ; but, nevertheless, one of the highest moUusks 

 may surpass in organization one of the lowest fishes, or an articu- 

 late creature a mollusk. The author considers such great divisions 

 of animals, as well as minor ones — the gasteropodous moUusks, for 

 instance — as realities, and not mere abstractions ; and that they 

 are independent of the circumstances of food, habitat, locomotion, 

 &c., just referred to. So great, however, are these disturbing 

 influences, that they often produce an extraordinary external 

 resemblance or pseudo-analogy between animals of a very difl'erent 

 nature, as between a Chiton and an Oniscus, and they are con- 

 nected intimately with, though not the cause of, what we call 

 specific or generic distinctions. Aerial life, in contradistinction to 

 aquatic, raises mucb the character of the locomotive organs ; yet 

 this is subordinate to type : hence the creeping Mollusk appears 

 to have commonly a higher organization than the flying Insect. 



The cartilages of Sepia have a true resemblance to those of 

 a Skate, and the Cirrhipede truly connects the Mollusk with the 

 Crustacean. The author regards Dentalium as a gasteropod, differ- 

 ing in this respect from Lacaze-Duthiers, whose beautiful paper, 

 however, renders it supererogatory to say anything more on this 

 animal, except that the author believes that the presence of the 

 spiniferous tongue, of a proboscis, and the nature of the food, are 

 favourable to his view : he also takes the feathery tufts to be the 

 branchiae. 



The anatomy of Aspergillum is similar to that of Fholas; 

 its mantle, however, is all but closed in front, and ends in an 

 obliquely-set muscular disk, applied to the internal surface of the 

 rose of the so-called arrosoir, the openings of this part of the shell 

 giving exit to certain processes and fimbriae of the fleshy disk, — 

 a narrow slit being also left in both the muscular and shelly disks 

 for the exsertion of the small, compressed and curved foot. The 



