596 HISTORY OF SYSTEMS. 



distinct and peculiar order to be called Phlebenterata. 

 This order he divided into families as follows : — 



PHLEBENTERATA. 



Gasteropod Mollusca with an imperfect circulation or 

 none, and without respiratory organs properly so called. 



Fam. 1. Enterobranchiata. Intestine branched; 

 the branches prolonged into the exterior appen- 

 dages. 



Tribe 1. Enterobranchiata proprement dits. Ap- 

 pendages isolated, more or less nume- 

 rous. The genera are : 

 Eolida, Calliopea, 



Eolidina Casolina ? 



Zephyrina, Glaucus ? 



Amphorina, Etc. 



Tribe 2. Ent. remibranchiata. Appendages 

 united into the figure of a fin. The 

 genera are : 

 Acteon, Placobranchus ? 



Acteonina, Etc. 



Fam. II. Dermobranchiata. Intestine very simple, 

 in the form of a few pouches ; no exterior ap- 

 pendages. The genera are : 



Pelta. Chalidis.* 



Although founded on other considerations, this order 

 coincides in most respects with De Blainville's Polybranches ; 

 and the tribe of normal Enterobranchiata is exactly coequal 

 with his family " Polybranches tetraceres." The Phleben- 

 terata have, according to M. de Quatrefages, a relationship 

 with the radiated animals on the one side, and with the 

 Annelides on the other ; and altogether his observations 

 would have been eagerly impressed by Mr. Swainson into 

 the proof of his view of the inferiority of the Nudibranches 

 in the class, and of their osculant tendency to his Molluscan 

 Planariae. Unfortunately, however, scarcely were M. de 

 Quatrefages' views made public before they were questioned 

 and repudiated. Souleyet at once pronounced, with a too 

 firm decision, that the anatomy on which the foundation of 

 the order rested was erroneous ; and his decision received an 

 immediate answer in the affirmative from the most competent 



* Sur les Mollusques Gasteropodes PliMbenter^s in Ann. des Sc. Nat. 

 (1844), i. p. 129—179. 



