MOLLUSCA GASTEROPODA. 425 



nervous system with an cesophageal ring, the eyes and 

 auditory organs, and especially also by the tongue. The 

 latter, it must be confessed, differs from that of the other 

 Gasteropoda ; it is very narrow, and consists only of a 

 longitudinal row of unciform plates, so that I would com- 

 pare it with the middle row of plates, which is very distinct 

 in most Snails (Snecken) ; consequently in this case the 

 lateral plates, which in other divisions are often very nume- 

 rous, are wanting. That the genus Glaucus, which the 

 author places here only interrogatively, is in reality properly 

 so placed, I can confirm from my own researches on the 

 oral organs ; I am also acquainted with the oral organs of 

 Eolidia. 



The author subdivides the order, which he characterizes as Gasteropoda 

 \\ith incomplete or deficient circulation, aud without special respiratory 

 organs, into two families. 



1. Eiiterobraiichia. In these the intestine is branched, and the branches 

 are prolonged into external appendages. These appendages are either 

 separate (Euterobrauchia sensu strictiore) with the genera Eolidia, Eolidina, 

 Zephi/fiiia, Amphorina, Cattiopcea, Carolina (?) Glaucus (?) ; or they are united 

 and remiform (Euterobranchia remibranchia) with the genera : Action, 

 Actceonia, Placobraiickus (?). 



2. Dermobranchia. They have a very simple intestine, in the form of 

 sacculi, few in number ; no external appendages. In this division are the 

 genera Pel/a and CItalidis. 



The new genera are characterized by the author as follows : 

 Zephyriiia (is Venilia, afterwards Proctonotus, Alder and Hancock). Head 

 indistinct ; four tentacles, the anterior broad and thin, the posterior long 

 conical ; body attenuated anteriorly and posteriorly ; two eyes at the base of 

 the posterior tentacles ; very numerous appendices respiratoriae on the sides 

 of the head and body, on the former in a single row ; foot thick, longer 

 posteriorly than the body. Mouth armed with two strong 1 , lateral, horny 

 teeth, and a horny palatal plate ; the abdominal vessels give off a multitude 

 of cseca in the cirrhi of the body ; brain with four evident ganglia. One 

 species, Z. pilosa, 



Actceon, Okeu. Head distinct, two tentacles, behind which, occasionally 

 at some distance, are two eyes ; body flat, oval, short, on the sides two 

 lamellated expansions, which unite behind the body, and are produced 

 posteriorly; foot projecting before the mouth, only under the body, so that 

 the appendages project free ; anus posterior in the middle above the point of 



