4 PROCEEDINGS OP THE NATIONAL MUSEUM Vol. 68 



especially in regard to " the total absence of a carina, and in having 

 a more smooth and polished surface, as well as a declining and more 

 oblique aperture than P. trlvolvis.'''' Whether one would say that 

 P. gldbratus has " a more profound and much more regularly con- 

 cave umbilicus than P. trivolvis " ^ is doubtful. 



The type of P. glabratus has not been found, and hence the de- 

 scription is our only guide for the species. Apparently Say's cita- 

 tion of " near Charleston, S. C," was unfortunate, and probably he 

 was dealing with a Florida specimen. At least no other specimens 

 of P. gldbratus have been recorded from the vicinity of Charleston. 

 All things considered it seems best to accept, for the present at least, 

 the flat, glossy shell of Florida interpreted by Pilsbry and Walker 

 as P. glahratus Say, as being the species described by Say under 

 that name. In the Academy of Natural Science of Philadelphia the 

 specimen catalogued under 21379 is labelled in Say's handwriting 

 " P. glahratus Say, S. Carolina." On the exhibition label (but not 

 in Say's writing) the specimen is said to be a cotype, but the specific 

 name P. gldbratus has been crossed off. It seems to be a small but 

 typical trivolvis. It seems likely that Say's label has been shifted 

 from the specimen to which it originally applied. 



The shell figured by Binney as P. glabratus has been identified by 

 Pilsbry as P. tumidus Pfeiffer. As a rule this species is more com- 

 pressed than is usual with P. trivolvis and this seems to have led 

 Binney and others to believe that it is the P. glahratus described 

 by Say. 



P. tumidus Pfeiffer was figured by Binney as P. glabratus and 

 belongs in the section Pierosoma with P. trivolvis Say and P. duryi 

 Wetherby, while the glossy, recent shell now accepted as P. glabratus 

 Say, and the Pliocene fossil species, P. co7ianti Dall, P. disstoni Dall, 

 and P. preglabratus Marshall belong in the section Planorbina. 

 P. glabratus and the three fossil forms just mentioned show a verj'^ 

 near relationship to recent West Indian and northern South Ameri- 

 can forms such as P. olivaceus Spix and P. guadalupensis Sowerby. 



EXPLANATION OF THE PLATE 

 (All figures multiplied by I14 diameters) 



Fig. 1. Plunorhis (PlanorMna) preglahratus, new species. Spire. 



2. Planorhis (Planorbina) preglahi-atiis, new species. Front. 



3. Planorhis (Planorbina) preglabratus, new species. Umbilicus. 



4. Lymnaea (Pseudosuccinea) aperta, new species. 



5. Lymnaea (Pseudosuccinea) barberi, new species. 



B When referring to " umbilicus," " base," and " spire " it must be remembered that 

 Say described these species as sinistral. 



o 



