REPORT ON ZOOLOGY. 215 



relative degrees of organization. Thus, he considers the Uete- 

 roporfa,' comprising the genera Carinaria, Firola, &c., as de- 

 serving to be placed at the head of all the MoUusca, and as 

 forming the transition to the Fish, an opinion which few will 

 be inclined to adopt besides himself. 



In 1819 appeared the first numbers of that splendid work 

 which M. de Ferussac has devoted to the Land and Freshwater 

 MoUusca, a work which for beauty as well as accuracy of illus- 

 tration has perhaps never been surpassed. It is principally, 

 indeed, to this department of the subject that De F(^russac's 

 labours have been directed, and no one has done more towards 

 elucidating the history of that immense assemblage of species 

 which belong to the Linnwean genus Helix. In order, however, 

 to point out the relation between the land and freshwater genera 

 and the rest of the MoUusca, he has added a general arrange- 

 ment of all the Molluscous animals, which though nearly the 

 same as that of Cuvier, presents nevertheless two or three slight 

 modifications. Thus, before arriving at the classes, we have a 

 primary division into two sections, grounded on the presence or 

 absence of the head. The first section, or that of Cephalous 

 MoUusca, includes the first three classes of Cuvier. The se- 

 cond, or Acephalous section, comprises the classes Cirrijieda, 

 Brachiopoda, Lamellihranchia (name taken from Blainville), 

 and Tunicata, this last being admitted as a group of a higher 

 denomination than that assigned to it by Cuvier. There is also 

 a slight difference in the subordinate divisions. Thus, the Cepha- 

 lopoda are divided into the two orders of Decapoda and Octo- 

 poda*. Amongst the Gasteropoda, we find a new order esta- 

 blished for the reception of the Operculated Pulmonifera. It 

 may be stated that Ferussac's work, which for some time was 

 interrupted, has been recently recommenced, and it is much to 

 be desired that it may yet be completed according to the original 

 plan. 



In 1820, Schweigger published in Germany a Manual of the 

 Inarticulate Invertebrate Animalsf. In this work, which I have 

 not seen, the arrangement of the MoUusca is said to be on the 

 whole similar to that of the R^gne Animal. 



In 1821, Mr. Gray published in the London Medical Repo- 

 sitoryX * new systematic arrangement of the MoUusca, founded 

 upon the internal organization. In this system, one of the 

 principal features is an entirely new nomenclature for the pri- 

 mary divisions, which constitute seven classes, in other respects 



• These groups are adopted from Dr. Leach. See his " Synopsis of the Orders, 

 Families, and Genera of the Class Cephalopoda," in his Zool Miscell., vol. iii. 

 p. 137. \ Handbuch der Natargeschichte, Sfc. 8vo, Leips, 1820. 



X vo\. XV. p. 229. 



