On the Shells of the Louisiade Archipelago. 199 



XXII. — On the Land- and Freshivater- Shells of the Louisiade 

 Archipelago. By Edgar A. Smith. 



[Plate XIII.] 



The British Museum has recently received from Mr. Basil 

 Thomson a very interesting collection of land- and freshwater- 

 shells made by him in some of the islands of the Louisiade 

 Archipelago. In naming these specimens it has been neces- 

 sary to study what has been written upon the shell-fauna of 

 these islands, and I have thus got together a complete list of 

 the known species *. 



The first and only collections of any extent from this locality 

 which have come to Europe were those made by MacGilli- 

 vray during the voyage of the * Rattlesnake ' in May, June, 

 and July 1849. 



Most of the species proved to be new, and the majority 

 were described and figured by Forbes in the second volume 

 of MacGillivray's narrative of the voyage. 



About half a dozen additional new forms have since been 

 described by Pfeiffer, Cox, Angas, and H. Adams. 



The present collection consists of fourteen species of terrestrial 

 forms, ten of which are new, and nine freshwater species. 



The most important discovery made by Mr. Thomson is that 

 of the four new species of Pupinella, one among them beingstill 

 larger than the P. grandis of Forbes. They are remarkable 

 in presenting curious modifications in the labial slit or notch ; 

 indeed in two of them this feature is so abnormal that it might 

 almost be considered of subgeneric importance. Mr. Gwat- 

 kin, however, who has kindly examined the radula of P. Mac- 

 gregori and P. rosselianaj observes : ^' there is certainly nothing 

 in the radula to call for subgeneric distinction." 



Fifteen land-shells have already been recorded from the 

 Louisiade Islands, and Mr. Thomson has now added eleven 

 others, making, together with three forms collected by Mac- 

 Gillivray and not recorded by Forbes, a total of twenty-nine. 

 With the exception of the Auriculida3 and of Helix Boyeri 

 and H. co7iiformis^ about the locality of which there is some 

 doubt, all the species are peculiar to these islands. 



Of freshwater forms only a single species has hitherto been 

 noticed, namely Neritina diadema. I now enumerate fifteen 



• With tlie exception of Nos. 9, 11, 12, and 14, all the species are in 

 the Museum. 



