190 SOLENOCONCHIA. 



among the Mollusca may now be considered settled. 

 Its symmetrical organization and habits connect it with 

 the Acephala ; its spinous tongue, indicative of a head, 

 allies it to the Gasteropoda. Its shell, although univalve, 

 is tubular and pervious, never corneal or spiral ; in all 

 these respects it differs from the shell of Patella, which 

 is never tubular or pervious, but always conical and 

 when young exhibits a distinct spire. Its relation to 

 the adult Fissurella is merely one of analogy. For 

 all these reasons I see no alternative but to adopt the 

 opinion of the learned French academician by making 

 it the type of a separate class. Argenville, in his 

 ' Zoomorphose ; (1757), gave the first idea of the ani- 

 mal. De Blainville called them ' Cirrobranches/ mis- 

 taking the tentacles for gills. Deshayes and Clark un- 

 fortunately tripped after him ; and both appear to have 

 made several mistakes, although of a contradictory 

 nature, with regard to the anatomy of the animal. 



" Velut silvis, ubi passim 

 Palantes error certo de tramite pellit ; 

 Ille sinistrorsum, hie dextrorsum abit ; unus utrique 

 Error, sed variis illudit partibus." 



It is unnecessary to notice the attempts of other syste- 

 matists, who, so far from contributing anything to our 

 former minimum of knowledge, did their little best to 

 lead us also astray. I may add that the views of Lacaze- 

 Duthiers have been most satisfactorily confirmed by an 

 elaborate essay of Sars on his Siphonodentalium vitreum, 

 which is perhaps the type of a new family of the present 

 class. 



