404 THE TERRESTRIAL MOLLUSCA INHABITING 



GENUS DIADEMA, Pease. 

 J). PARVA, Pease. 



Pterocyclos? parva, Pease, Amer. Jour. Conch., 1865, p. 290; 1866, p. 82, PI. 5, fig. 8. 



Diadema parva, Tease, Amer. Jour. Conch., 1868, p. 158, PI. 12, fig. 13 (Operculum); Proc. 



Zool. Soc, 18tl, p. 415. Pfeiffer, Mon. Pneum., Suppl. 3, p. 56. 



Pterocyclos (Diadema) parvus, Mart. & Langk. Don. Bism., p. 58. • 



Oarrettia parva, Paetel, Cat. Conch., p. 124. Schmeltz, Cat. Mus. Godeff., v., p. 100. 



Found in the greatest profusion on the ground in forests at Aitutaki, where it 

 appears to be peculiar. 



Its turbinate form, brown color, and quadricarinate body-whorl will readily 

 distinguish it. 



All of Mr. Pease's specimens were collected by me, and though the locality 

 was well known to him, yet from some unaccountable reason he suppressed the 

 locality of this, and most of the other new species he received of me. When he 

 published the genus Diadema he gave the correct locality of this species, but in 

 his list of Polynesian land shells refers it to Rarotonga where it does not occur. 



D. BiANQULATA, Pease. 



Cyclostoma hiangulatum, Pease, Proc. Zool. Soc, 1864, p. 614. 



Diadema Uangulata, Pease, Proc. Zool. Soc, 1811, p. 415. Pfeiffer, Mon. Pneum., Suppl. 3, p. 56. 



Cyclophorus (Ostodes) biangulatus. Martens & Langk., Don. Bism., p. 58, PI. 3, fig. 16. 



Oarrettia Scalar if ormis, Paetel, Cat. Conch., p. 124. 



Oarrettia biangulata, Schmeltz, Cat. Mus. Godeff., v., p. 100. 



? Cyclophorus biangulatus, Pfeiffer, Mon. Pneum., Suppl. 3, p. 114. 



? Cyclomorpha biangulata, Pfeiffer, 1. c, p. 234. 



" Found in equal abundance, and associated with the preceding species, but not 



obtained in any other part of the group. Mr. Pease's habitat "Atiu," as given 



in his " List of Polynesian Land Shells," is entirely gratuitous. He received the 



specimens of me carefully labelled Aitutaki. 



Had the above author included it in his list of Diadema when he first published 

 the genus, the doubts and confusion in regard to its generic position would have 

 been avoided. 



His type specimens were collected by me at Moorea, one of the Society Islands, 

 where I found a single small colony, probably introduced. When he described it 

 he gave the vague locality " Central Pacific." 



It differs from parva in its more elongate shape and tricarinate body-whorl. 



D. EOTELLA, Pease. 



Diadema rotella. Pease, Amer. Jour. Conch., 1868, p. 158, PI. 12, fig. 13 ; Proc. Zool. Soc, 1811, 



p. 415. Pfeiffer, Mon. Pneum., Suppl. 3, p. 56. 

 Pterocyclos {Diadema) rotella, Paetel, Cat. Conch., p. 119. 

 Oarrettia rotella, Schmeltz, Cat. Mus. Godeff., v., p. 100. 



