13 



made by conchologlsts among the Lamcllibranchiate Conchifera. He 

 regards Anomia as being in some measure intermediate between this 

 order and the Brachiopoda ; and in illustration of this view describes 

 with some detail the structure of the animal of that genus. 



Mr. Garner then adverts to the mode of growth of the shells and 

 to their structure, and considers them in the variations in form 

 which some of them undergo in their progress from the embryo to 

 the adult state. He dwells also on the diversity of form assumed by 

 the several groups of Bivalves, and shows in what manner these are 

 occasioned by the form of the animal that produces the shelly cover- 

 ings ; referring to the foot especially as exercising in this respect a 

 very remarkable influence. 



The general review of the extei^nal form of the animal is succeeded 

 by an account of the several systems of which it is composed. These 

 are treated of in the following order : 1. Muscular system ; 2. Ner- 

 vous system; 3. Digestive system; 4. Circulating system ; 5. Respi- 

 ratory system ; 6. Excretory system ; 7. Cilia (and into this part of 

 his subject the author enters with more than usual detail) ; and, 8. 

 Reproductive system. Under each of these heads a rapid review is 

 taken of the principal variations that occur in the order, and the 

 illustrative examples referred to are generally numerous. 



Finally, the author devotes a section of his paper to the diseases 

 and the parasites of the animals on which he treats. 



In conclusion, Mr. Garner submits the subjoined tabular view 

 of an 



Anatomical Classification of the Lamellibranchiate Conchi- 

 FEROus Animals. 



With but one adductor muscle. Monomyaria, La7n. 



Tentacles very long, not distinct from the bran- 



chiee ; an additional muscular system Anomia. 



Tentacles short, separate from the bronchia. 



No foot Ostrea. 



A foot. 



Branchia disunited medianly. 



Foot long, cylindrical ; ocelli at the edge 



of the mantle Pecten. 



Foot short, thick, with a disk at the ex- 

 tremity, from the centre of which 

 depends a pedicellated oval body; 



ocelli Spondylus. 



Foot compressed ; no ocelli Lima. 



Branchite conjoined medianly Vulsella.* 



