INVERTEBRATE PALEONTOLOGY. 313 



subsequently-published genus Amaurqpsis, and one that .seems to be either a 

 MacrQcheilus, Phillips, 1841, or a Naticopsis, McCoy, 1844. 



Hence, if we take the first species mentioned under Euspira as its type, 

 this would very probably make Lunatia a synonym of that genus. For 

 reasons elsewhere explained, however, the rule of always taking the first 

 species mentioned under a genus as its type, cannot be carried out in conchol- 

 ogy without creating intolerable contusion among the older genera ; while 

 there will probably always remain some doubts whether or not the species 

 N. glauconoidcs of Sowerby really possessed the corneous operculum of 

 Lunatia. On the other hand, if we follow the much better and more gener- 

 ally adopted rule of allowing the first authors who divides a complex 

 genus, to separate any of his included species under a new generic name, 

 so long as any previously-unnamed type is left to inherit the original 

 name, it may be a question whether we should not only retain the name 

 Lunatia for the group to which Dr. Gray applied it, but retain Euspira for 

 the group subsequently named Ainauropsis by Morch, or for some of the 

 other included types ; though it, of course, could not be made to replace either 

 of the older genera Ampull 'ina or Straparollus. For the reasons above stated, 

 it seems undesirable to replace Lunatia, founded on a well-known type, by 

 Euspira; at least until the question has been decided in regard to which ot 

 the species originally included under that name is to be viewed as the type, 

 and whether or not that type has beyond doubt the corneous operculum of 

 Lunatia. 



Dr. Stoliczka has correctly remarked that H. and A. Adams were in 

 error in citing Euspira, Agassiz, as a synonym of Ampullina ; and, according 

 to M. Deshayes, they were also equally in error in applying the name Ampul- 

 /ina, Lamarck, to the group including the recent Natica J/uctuata, Sowerby. 

 Lamarck's genus was founded on such shells as Natica segaritina, Des- 

 hayes, and N. patula, Lamarck, which have the inner lip not near so thick- 

 ened in the middle as N.jiuctuata, and also differ in having this lip a little 

 free and carinate below, the carina being continuous with the lower margin 

 of the aperture. Dr. Stoliczka, however, seems to have also fallen into an 

 error in citing Globular/a, Swainson, as a synonym of Euspira ; Swainson's 

 name being apparently a synonym of the true Ampullina, Lamarck (not of 

 H. and A. Adams). 



Again, H. and A. Adams were unfortunate in citing Dcshayesia as a 

 40 H 



