MOLLUSC A. 41 



separate. It includes the whole of the marine species of the 

 Linnaean genera of turbinated univalves. Into this order, 

 Cuvier, from the consideration of other characters, has in- 

 serted the genus Cyclostoma, which, according to the cha- 

 racters indicated by the respiratory organs, belongs to the 

 Pulmones. 



In the seventh order, termed Scutibranches, the bran- 

 chiae are similar to those of the preceding order, but the 

 sexes are united, each individual being capable of impreg- 

 nating or being impregnated. The shells in general are 

 cup-shaped, and destitute of a lid. It includes the genus 

 Halyotis, and many species of the old genus Patella. In 

 the last order, called Cyclobranckes, the branchiae appear in 

 the form of small leaves or pyramids strung round the under 

 margin of the cloak. They enjoy a hermaphroditism simi- 

 lar to those of the preceding order. The species of the 

 genus Patella which are allied to the vulgata, and the genus 

 Chiton, are included in this order. 



In the fourth class, or ACEPHALA, he includes the bivalve 

 shells, distributing them into families, from characters near- 

 ly similar to those which we have pointed out as having 

 been previously employed by Poli. 



The fifth class, termed BRACHIOPOPA, contains animals, 

 resembling those of the preceding class in having a cloak of 

 two lobes, but these are always open. The branchiae con- 

 sist of small leaves placed on the inner margin of each lobe. 

 In place of a foot they have two retractile fleshy arms, 

 which are extensile. This class includes the Patella unguis 

 of Linnaeus, the genus Terebratula and the Patella anomala 

 of Miiller. 



The class CIRRHIPODA, distinguished by the articulated 

 filaments with which the animals are furnished, contains the 



