CHAP. I. SYSTEM OF CUVIER. 25 



Nummulites. Baculites. SECT. III. 

 Nautilus. Ceph. Cepiaria. 



Ammonites. SECT. II. Octopus. 



Orbiculites. Ceph. Monothalama. Loligopsis. 



Ammonoceras. Argonauta. Loligo. 



Turrilites. Sepia. 



; ORDER V. HETEROPODA. 



Carinaria. Pterotrachia. Phylliroe. 



(21.) The system of M. Cuvier differs, in many re- 

 spects, from the above. The Mollusca form the second 

 great division into which this admirable anatomist divides 

 the animal kingdom. These he distributes under six 

 principal classes : 1 . Cephalopoda, or cuttlefish ; 2. 

 Pteropoda, or clios ; 3. Gasteropoda, an immense and 

 heterogeneous assemblage, which we shall presently 

 notice in detail ; 4. Acephala, or bivalve Testacea, at 

 the end of which he introduces the tunicated Mollusca 

 (Tunicata Sav.) ; 5. JBranchiopoda, or anomian shells; 

 6. Cirripedes, or barnacles. The great variety of ani- 

 mals brought together in the third order, Gasteropoda, 

 obliges our author to divide it into others, the names and 

 contents of which are as follows : 1 . PULMONIA, con- 

 tains the slugs and snails, both terrestrial and fluviatile. 



2. NUDIBRANCHIA, includes all the naked marine Tes- 

 tacea without shells, as Triton, Doris, Thethys, &c. 



3. INFEROBRANCHIA, consists but of two genera, Phyl- 

 lidia and Diphyllidia. 4. TECTIBRANCHIA, compre- 

 hends the Bulla family and the Aplysia. 5. HETERO- 

 PODA, embraces the Firoles and the Carinarice. 6. PEC- 

 TINIBRANCHIA : under this order, arranged in sections, 

 are placed the whole of the Trochus and Turbo families, 

 together with the greatest part of the marine univalve 

 Testacea. 7- TUBULIBRANCHJA, is limited to the genera 

 Vermetus, Magilis, and Siliquaria. 8. SCUTIBRANCHIA, 

 contains Haliotis, Fissuretta., and Emarginula : while 

 the 9th and last order, CYCLOBRANCHIA, consists but 

 of Patella and Chiton. To go into further detail will 

 be needless, since the student will at once arrive at a 

 general idea on the contents of these groups, by the indi- 

 cations already given. 



