160 On the Systematic Arrangement of 



ence of food, of the presence or absence of a jaw, of the 

 aculeate or quadrate form of teeth, supposed to exist between 

 the Vermivora and Phyllovora, we find these characters 

 shared irregularly by both sections, and consequently we 

 abandon them. 



OLEACiNiDiE (p. 13). — In the description of the teeth the 

 term aculeate, rather than recurved, better expresses their 

 thorn-shaped outline. In our descriptions of the lingual 

 membranes, we have often called these teeth uncini, and 

 with less judgment used the same term for the quadrate 

 marginal teeth of some of the HelicidcB. It would be better 

 in all cases to retain the names central, lateral and marginal 

 for the three forms of teeth. 



Cylindrellid^. — We no longer consider this a distinct 

 family. Even while our work was passing through the press 

 the presence of a jaw was discovered by one of us.* We 

 also misapprehended the character of the teeth, which have 

 since proved to be simply a modification of the form usual in 

 the HeliciddB. We propose, therefore, to place the species 

 referred to Oi/lindrellidcE, and also of Macroceramus referred 

 to OrthalicincE, in the family Helicidm, before the genus 

 Bidhmdus. 



Messrs. Crosse and Fischer (Jour, de Conch., January, 

 1870), after a thorough study of the jaws and lingual mem- 

 branes of numerous species, proposed to separate the Gylin- 

 drellidoe as a family, supporting their views entirely upon 

 the jaw and teeth, both of which we have found unreliable. 

 The kind of jaw supposed by them to be peculiar to the 

 family has been detected by us in various species of Bidimu- 

 lus, "and in one of Helix (see Ann. Lye. N. H. N. Y., x., 

 79). The type of palmate teeth, also, which Messrs. Crosse 

 and Fischer describe as charticteristic of the family is not 

 constant, as we find it entirely wanting in Macroceramus 

 Gossei. (See American Journ. of Couch, vii, pi. 17, figs. 

 9, 11, 12.) 



*Blaud, Amer. Jour, of Conch. IV. 1868. 



