150 LITTORINID SE. 
Here perhaps is an explanation of some of the differences 
in allied forms? Can, for instance, my Singapore specimens 
catalogued as L. pallescens var. erronea, and those as L. arbori- 
cola var. philippiana, be the different sexes of one species ? 
Long. 16, diam. 975 mil. [Generally a little smaller. ] 
The differences from the typical form are probably due to 
my var. delicatula living in slightly brackish water? Reeve’s 
L. tenuis from the Philippines seems to be an allied form ? 
20 Port Canning and False Point; coll. Colonel G. B. Mainwaring, 
Dr. F. Stoliczks, J. Wood-Mason and G, Nevill, Esqrs. 
Of equally fragile texture, but easily distinguished from the 
female form by the less produced spire, even less developed 
keel at periphery, and especially by the conspicuously distended 
aperture and rounded columellar margin at base; several speci- 
mens have one or two varices behind the peristome, which is 
occasionally ‘“subduplex.” The coloration is, if possible, 
even more beautiful and variable! Long, 14, diam. 81 mil. 
Gibbons, Q. J. Con. 1878, p. 339, states that specimens of Lit. 
intermedia and angulifera become less solid as the water in 
which they live is less salt; I am not sure that this applies to 
the form under consideration as immediately associated with 
my var. delicatula, may be found normally solid Lit. inter- 
media and the very thick-shelled Lit. melanostoma. 
var. subintermedia, nov. 
10 Port Canning and False Point; coll. Colonel G. B. Mainwaring. 
Long. 154, diam. 9 mil. 
Most remarkable and interesting specimens, combining many 
of the characters of DL. intermedia, Phil., with those of LZ. 
conica. Can they be a hybrid race ? 
The above are what I take to be the 9 form. 
8 Port Canning ; coll. Colonel G. B, Mainwaring. 
These are doubtless males. 
47. Littorina albicans. 
Littorina albicans, Metcalfe, P. Zool. S., 1852, Borneo, 
3 Loc. ?; exc. Dr. F. Stoliczka. 
