214 FOURTH REPORT — 1834. 



Lingula, Terebratula, an d OrAiCM^a, which had previously formed 

 a part of the class last mentioned. The Cirrhopoda comprise 

 the two genera Anatifa and Balanus, which Cuvier considers 

 as in some respects intermediate to the Molluscous and Articu- 

 lated Animals. 



The benefits conferred upon this department of zoology by 

 Lamarck belong to a period of time somewhat anterior to the 

 publication of the R^rpie Animal. We may, however, make a 

 few remarks on the system adopted in the fifth and two suc- 

 ceeding volumes of the second edition of the Animanx sans 

 Vert^bres, which appeared in the years 1818 — 1822. Perhaps 

 it is in the details of the science, the grouping of genera, and the 

 characterizing an immense number of new species, that Lamarck's 

 tact and penetration appear most conspicuous. His leading di- 

 visions present several peculiarities which are scarcely warranted 

 by the organization of these animals. Thus, he has separated 

 altogether from the Mollusca the Naked Acephala, and made 

 of them a distinct class mider the name of Tuniciers, which he 

 refers to quite another place in his system, below the Articulated 

 Animals which intervene. Again, the rest of Cuvier's Mollusca 

 he divides into only three classes, which we are naturally led to 

 infer he considers therefore as groups of equal value. The first is 

 that of CirripMes. The second, or Conchif^res, answers to the 

 Testaceous Acephala of Cuvier, including also the Brachiopoda. 

 The third, to which Lamarck restricts the name of Mollusques, 

 comprises all the remaining classes of the R^gne Animal. The 

 groundof primary subdivision in Lamarck's second class is more 

 entitled to our regard than that on which his higher groups are 

 established, although not particularly noticed by Cuvier. It is 

 the niunber of the muscles of attachment and the impressions 

 caused by them on the shell, points to which Lamarck was the 

 first to call the attention of naturalists in a memoir in the Ann. 

 du Mus. for 1807- These give rise to the two orders of Dimy. 

 aires and Monomyaires. The secondary groups in this class 

 are founded on the form and structure of the shell, the situation 

 of the ligament, and the form of the foot of the animal ; the 

 families resulting from these principles of arrangement being on 

 the whole natural, though not in all cases distinguished by cha- 

 racters of the same importance. The third class, Mollusques, 

 is divided into five orders, one of which answers to the class 

 Pteropoda of Cuvier, and another to the Cephalopoda of the 

 same author : the remaining three are formed out of Cuvier's 

 class Gastet'opoda, and bear the names of Gast^ro/jodes, Tra- 

 chelipodes, and H.et4ropodes respectively. Li this part of his 

 system Lamarck has not only altered the value of some of 

 Cuvier's groups_, but adopted peculiar views with regard to their 



