184 PKOCEEDIKGS OF THE MALACOLOGICAL SOCIETY. 



Various authors have disafjreed in regard to the limits of the 

 Amnicolidae ; on the one hand it has been extended to include all the^ 

 not strictly marine llissoid genera, while on the otlier it has been sub- 

 divided on the most superficial characters. Doubtless when I'estricted 

 to embrace only the freshwater Rissoideoe with horny sub-spiral 

 opercula, it is a rather over-comprehensive group, but the anatomical 

 studies necessary to segregate the genera into families and sub-families 

 would require time all out of proportion to tlie results to be gained 

 in the present discussion. 



Family AMNICOLID^., Tryon, 1862. 



Shell small or minute, sub-solid, varying from globose to attenuate, 

 imperforate or umbilicate, whorls more or less inflated, sutures 

 impressed, aperture ovate and somewhat retracted below; animal 

 oviparous, rostrum short and broad, tentacles cylindrical, blunt or 

 tapering, foot short and broad, auriculated in front, rounded behind, 

 and more or less constticteil in the middle, operculum corneous and 

 paucispiral, with a sub-central nucleus ; habitat lacustrine and 

 fluviatile. 



Six more or less localized genera, Amnicola, Paludestrina, Flmnini- 

 cvla, Pyrgulopsis, Cincinnatia, and Brannerillus, occur in the present 



year. Aclanson's species is included and given a binomial name. His 

 group contains : (1) Bulinus perla {Plnnorbis bulla, MiilL, Bulla fonti- 

 nalis, Ij.) = Physa fontinalis; (2) B. turritus {Planorbis hirritus, Miill., 

 Bulla hyptiorum, L.) = Phijsa hypnoriim; (3) B. gelatinus {Planorbis 

 gelatinus, Miill.) = ? Pliysa fontinalis ; (4) B. Scnegalensis (Le Bulin, 

 Bulintts, Adanson). 

 1786. Scopoli, DelicicB Flora', ct Fauna; Insubrica>., i, p. 67, used Bulivius 



for a South American land shell belonging to Bonis, Albers, 1850. 

 From these data we may draw the following conclusions. 



Bulinus, Adanson, is not binomial and pre-Linntean, hence can only be 

 cited historically. 



Bulimus, Scopoli, 1777, may be based on Bulinus, Adanson, 1757, or it 

 may be based on some manuscript Bulimus of Adanson. No clue is given 

 to where Adanson may have used the name, therefore there is no way of 

 determining. If Bulimus, Adanson, was a manuscript name, it would 

 have to be cited as of Scopoli, however, as its first use in print. If 

 Bulimus is derived from Bulinus, Scopoli's attribution of the genus to 

 Adanson explains the derivation of the word, but the fact that he altered 

 the spelling and used the name for a group, in which Adanson's species 

 was not included, places it on a distinct nomenclatural basis, hence it 

 must be cited as of Scopoli in any event. Helix tentacula, L., has been 

 named by Dall as a type by elimination, thus giving it priority over 

 Bithynia, Leach, 1818. 



Bulinus, Miiller, is Bulinus, Adanson, adopted into binomial nomen- 

 clature. Adanson's species must go with it, in any event, since it is the 

 type by autonomy and subsequent elimination. 



Bulimus, Scopoli, 1786, makes it impossible to question Bulimus, 1777, 

 as a lapsus for Bulinus. Its use for a land shell does not concern the 

 applicability of the name for the species previously included. Scopoli may 

 have thought his species was aquatic. 



The similarity in orthography is undesirable, but does not affect the use 

 of the names. 



One species, Bulimus tentaculus, L., occurs as an introduced form in 

 the drainage of the Great Lakes and adjacent waters of North America. 



