348 balanjdjE. 



from the Falkland Islands and Tierra del Fuep;o, as far 

 north as Chiloe. Elminins, therefore, appears to he strictly 

 a southern genus. Elminius Kingii and modestus represent 

 each other on the American and Australian continents ; so I 

 believe E. plieatus, in New Zealand, represents E. simplex 

 in New South Wales and Van Diemen's Land. The species 

 are all attached to tidal rocks and shells. E. Kingii is some- 

 times attached to floating wood. At the Falkland Islands, 

 the last-mentioned species adhered to some rocks, in a 

 running brook of fresh water, at most eighteen inches under 

 high-water mark, so that for the greater part of each tide it 

 was exposed to absolutely fresh water. At Sydney I found 

 E. modestus adhering to oysters in a muddy lagoon, almost 

 separated from the sea, and apparently very unfavorable 

 for cirripedes. 



Affinities — This genus can be distinguished from Tetra- 

 clita only by the four compartments not being porose, and 

 by the basis being always membranous ; whereas, in Tetra- 

 clita purpurascens alone it is membranous. Elminius Kingii 

 and modestus, on the one hand, are closely allied together, 

 as are E. simplex and plicatus on the other hand. The last- 

 named species, in the characters of its opercular valves and 

 in its shell, comes nearest to Tetraclita. In T. rosea we have 

 seen that there is only a single row of parietal tubes, and 

 the outer lamina of the shell is strengthened (as, indeed, it 

 is in most of the other species of the genus, and in Balanus) 

 by small longitudinal plates or ridges, which are similar and 

 homologous to those on the internal basal edges of the pa- 

 rietes in three of the species of Elminius; so that the difference 

 in the structure of the parictes, in Tetraclita and Elminius, 

 is small. 



1. Elminius Kingii. PL 11, fig. 6 a — 6 e. 



Elminius Kingii. J". E. Gray. Zoological Miscellany, p. 13, 1831. 



— Leachii. King and Broderip. Zoological Journal, vol. 5, 



1832 — IS 3-1, p. 331, and appendix to King 

 and Fitzroy's Voyages. 



— — G. B. Soicerby. Genera of Recent and Fossil 



Shells, Plate. 



