10 Couthouy’s New Species of Mollusca 
slightly compressed and minutely serrated at their sides, 
rather shorter than the frontal pairs; eyes inconspicuous ; 
branchial cirri reddish-brown, disposed along each side 
of the back in seven clusters, rather remote from each 
other, each cluster formed of five cirri, the second and 
third pairs rather larger or longer than the rest; the 
middle of the back is entirely naked its whole length, 
and has the same elevation in its centre with those 
already described; foot the width of the body, entire 
and very transparent, the viscera showing very plainly 
through it; genital organs upon the right side below the 
first group of branchie ; anal orifice somewhat higher up, 
between the third and fourth group same side. 
Ozservations. The genus Eolis, Eolida or Eolidia, 
as it is variously denominated by authors, was separated 
together with the Tergipedes, by Cuvier, from the genus 
Doris of previous naturalists ; from which Bruguière also 
established the genus Cavolina. Zoologists are, however, 
in the present state of knowledge, not of agreement 
whether the genera Tergipes and Cavolina should be de- 
finitively admitted or rejected. Among later authorities, 
De Blainville has given them a place in his “ Man. de 
Malac. et de Conchyl.," with the remark, that the latter, 
might, without inconvenience, be united to the Eolides ; 
while Des Hayes, in his recent edition of Lamarck, advo- 
cates the union of all three genera, or the considering 
them, at least for the present, as merely sections. Un- 
der these circumstances I have preferred placing the 
three species just described under one genus, and adopt- 
ing the name of Eolis, originally given by Cuvier. 
Of the organization of these animals, but little, com- 
paratively speaking, is yet known. Lamarck, who pro- 
bably never saw them alive, supposes that they are inca- 
