452 MR. HARPER PEASE ON POLYNESIAN LAND-SHELLS. [May 2, 



occur, represented by H. bursatella, Gld. They differ from the 

 type in being angulate at the periphery, with the spire more ele- 

 vated, and the whorls more plain. Their greatest peculiarity, and 

 one by which they may be easily recognized, is the shape of the 

 umbilicus, which becomes at maturity partly covered over by the 

 base of the last whorl, thus becoming cavernous. 



Two species have been described from Tahiti and the Hervey 

 Islands, viz. jacquinoti, Pfr., and fratercula, Pse., which evidently 

 belong to the above group, but are depressed and carinate at the 

 periphery, corresponding in their variation to stellula, Gld., at the 

 Hawaiian Islands. I add the following remarks on the synonymy 

 of the species. 



PlTYS BURSATELLA, Gld. 



Of this variable species I have had an opportunity of examining 

 several hundred specimens, and have also received a full series selected 

 from the collections of the American exploring expedition, and from 

 the late Mr. Cuming's type specimens of H. jacquinoti, Pfr. The 

 synonymy, as determined by Dr. Gould on the labels of distribution 

 issued by the Smithsonian Institution, and adopted in the following 

 catalogue, is correct, with the exception of H. oceanica, Guill., and 

 H. cavernula, Jacq. Of the synonyms determined as above, H. 

 excavata, Jacq., and H. coarctata, Pfr., are pure synonyms of the 

 type ; H. streptaxon, Roe, is an abnormal form, and H. turrieula, 

 Jacq., identically the same ; H. oceanica, Guill., which I exclude 

 from the synonymy, is described as being concavely depressed on its 

 base ; and no mention is made of the laminae in its aperture, which 

 are distinct and could not have escaped notice. Should the determi- 

 nation by Dr. Gould prove to be correct, H. oceanica, Guill., should 

 have precedence over H. bursatella, Gld., having been described 

 four years previously. 



H. jacquinoti, Pfr. {cavernula, Jacq.), differs from P. bursatella, 

 Gld., or any of its varieties, in being more depressed, acutely carinate 

 at the periphery, without epidermis (surface somewhat shining), its 

 ribs solid, more prominent, extending over the edge of the whorls 

 in a serrated manner, and all the whorls depressedly grooved concen- 

 trically at their middle. I have met with no species of its type in 

 collections from the Marquesas, and refer it therefore to Tahiti with 

 a doubt. The only other species of its peculiar form is P. frater- 

 cula, Pse., inhabiting the Hervey Islands. 



Pitys jugosa, Migh. 



Helix jug osa, Migh. Proc. Boston Soc. 1845, p. 19. 



Helix rubiginosa, Gld. Proc. Boston Soc. 1846, p. 1/1 ; Am. Exp. 

 Ex. 1852, p. 50, fig. 49. 



The above species ranges over all parts of the island of Kauai ; 

 it varies in being more or less openly umbilicate, and in the colour 

 being either wholly reddish brown or tessellated with a dusky yel- 

 lowish colour. 



