Pulmonifera of Maine. 51 



GEOGRAPHICAL DISTRIBUTION. 



A very few facts worthy of remark have been noted relative to 

 the geographical distribution of the terrestrial and fluviatile mol- 

 lusca of Maine. Though the area of the State is nearly as large 

 as the other five New England States together, embracing an 

 extent of 31,766 square miles of surface, we find as a general 

 thing an equable distribution of species in all its parts ; though 

 the occurrence of some species is more frequent in certain regions 

 of the State than in others. The Limnteida; appear to be confined 

 almost exclusively to the southern portions of the State. Among 

 the species occurring from one extremity of the State to the other, 

 we have Hyalina arborea, H. electrina, Conulus chersina, Striatura 

 milium, Patula striatclla, Mesodon albolabris, Succinea Totteni- 

 ana, S. avara, Vitrina limpida, Isthmia Gouldii, Helisoma bicari- 

 natus, Planorbella campanulatus, Menetus exacutus, Gyraulus par- 

 vus, and Unio complanatus. Of those more common near the 

 coast we find Strobila labyrinthica, Anguispira alternata, M. 

 albolabris, Vallonia minuta, Tachea hortensis, Zua lubricoidea, 

 Succ. ovalis, S. Totteniana, Zoogenetes harpa, Leucochila pento- 

 don, Pupilla badia, Isthmia Gouldii, I. ovata and I. milium. Of 

 the ones more common to the western and central portions of 

 the State, though many occur on the coast, are Triodopsis 

 dentifera, Mesodon Sayii, Helicodiscus lineata, Hyalina multi- 

 dentata, H. indentata, Planogyra asteriscus, Pseudohyalina exigua,"* 

 Punctum minutissimum, Tebennophorus Carolinensis, Pallifera 

 dorsalis, Limax canipestris, Isthmia simplex, Leucochila contracta, 

 L. corticaria, and Carychium exiguum, Triodopsis dentifera, Mac- 

 rocyclis concava, H. multidentata, P. asteriscus, L. corticaria. 



L. contracta and Gyraulus dilatatus are confined to a few places 

 many miles from the coast, while Tachea hortensis, Hyalina cellaria^ 

 Pseudohyalina minuscula, Isthmia milium, Pupilla badia and the 



