36 Moll 
MOLLOSCA. 
and its morphology as his basis (318). In the completed treatise (320) 
the scheme is given as follows : — 
Pelseneer further points out that the nearest allies to the Lamelli- 
Iranchiata in the Molluscan phylum are the Rhipidoglossa. Both are 
derived from forms, related to the dibranchiate Rhipidoglossa, that have 
not undergone torsion : to these hypothetical forms the name Prorhipido- 
glossa is given. 
MenIsgaux, working independently of Pelseneer, came to similar con- 
clusions. His preliminary sketch [ vide Zool. Rec. 1889, Moll. 23 (10)] 
appeared shortly after Pelseneer’s, and the final work, as a thesis, (279) 
in 1890. Menegaux’s classification differs principally in that he uses the 
