(hi a ufii- Ptdtinculale Cirripccle. 443 



Just as flic (luviatile .shells possess a w'uler raii^e and 

 int'ert'iitially greater powers of dispersal than terrestrial 

 niollusks, so do niiiiute land-shells gain more extended limits 

 tlian bulkier forms. If a collection of Tasmanian or New- 

 Zealand shells were put into a sieve, the shells that passed the 

 meshes would roui;hly represent those with a wide range, 

 and the shells retained those with a restricted one. That none 

 of the larger, but all the smaller, species of Fiji (continental 

 islands) are represented in Samoa (oceanic) is a signiricant 

 illustration which may explain how the micro-snail faunas 

 of Tasmania and New Zealand are, as Mr. Suter says, so 

 closely allied, while the macro-snail faunas repudiate any 

 relationship. 



Conclusion. — None of the species and about half the genera 

 of their respective land-molluscan faunas are common to 

 Tasmania and New Zealand ; this conimunity does not 

 embrace the Streptoneura. The common element for the 

 most part is represented by minute species and widespread 

 genera, and does not necessarily imply former direct land 

 communication. As a whole the two faunas are wider apart 

 than those of Britain and the Atlantic States of North • 

 America. 



Sydney, 

 Feb. 10, 1894. 



LI. — A new Pedunculate Cirripede. 

 By the llev. Thomas 11. H. Stebbing, M.A. 



[Plate XV.] 



TuiCHELASPis, gen. nov. 



Valves five; the scuta trifid ; the carina terminating in a 

 fork at its base. The mandibles with five or six teeth ; the 

 first maxillfe very slightly notched. In each cirrus t!ie two 

 rami are subequal. The caudal appendages are one-jointed, 

 spinose. 



The name of the genus is derived from Tpi';^7;Xo<?, cloven in 

 three, and acrTr/?, a shield. The characters are but little 

 removed from those of Dichelaspis '^ but since that name was 

 chosen by Darwin to displace the earlier names Octolasmis 

 and Heptolasmisj on the ground that those titles conveyed a 

 false impression, it seems impossible to retain Dichelasjyisj 

 meaning a bifid scutum, for a species in which the scutum is 

 very conspicuously tritid. 



