MOLLUSC A 391 



The question whether these forms — when sinistral — belong to Pkysa or Limnaea, 

 has for long proved to be a difficult one. Gould, when describing his Pkysa reticulata, 

 remarked " its form is so much that of a reversed Litnnaea that I am almost tempted to 

 consider it one." Pease, in his review of the Hawaiian species, stated that he was 

 "confident," having e.xamined the animals of several hundred specimens, that there was 

 no species of Pkysa in the Islands. He also remarked that sinistral and dextral 

 specimens of the same species may be found together. Prof. E. von Martens, in 1866, 

 expressed the view, here adopted, that these Hawaiian forms were really sinistral 

 species of Limnaea. 



As shewing how little the literature has been studied, I may remark that as late 

 as 1889 Mr Cooke (P. Zool. Soc. London, 1889, p. 142), when pointing out the 

 affinities with Limnaea of the so-called Pkysae of Australia, notes that " Tryon 

 mentions, but I have failed to trace on what authority, that sinistral Limnaeas occur 

 in the Sandwich Islands." 



Mighels described (P. Boston Soc. 11. p. 21) two species, /;W//f/a and umbilicata, 

 as Pkysae : according to Pease the types were destroyed by fire and, as the species 

 are unidentifiable from the diagnoses only, I have omitted them. 



(i) Limnaea aiilacospira Ancey. 



Limnaea aiilacospira Ancey, Naturaliste, (2) xi. (Dec. 1889), p. 290; Sykes, 

 P. Malac. Soc. London, in. pi. xiii. fig. 19. 



Hab. Maui (Ancey); Haleakala at 5000 feet, and lao Valley (Perkins). 



(2) Limnaea binom,inis, nom. nov. 



Pkysa sandwichensis Clessin, Conchylien-Cabinet, Pkysa, p. 342, pi. xlviii. fig. 7 



(1886). 

 nee Limnaea sandwichensis Philippi. 



Hab. Hawaiian Islands (Clessin). — Oahu, Mts. near Honolulu (Perkins). 



(3) Limnaea compact a Pease. 



Limnaea compacta Pease, Amer. J. Conch, vi. (1870), p. 6, pi. in. fig. 4. 



Limnaea ambigiia, Pease, t. c. p. 6, pi. in. fig. 5. 



Pkysa flavida Clessin, Conchylien-Cabinet, Pkysa, p. 364, pi. Li. fig. 9 (1886). 



Hab. Oahu (Pease). — (as L. ambigna) Kauai, Kapaa (Baldwin). — (as L. compacta) 

 all the Islands (Baldwin). 



F. H. II. 51 



