198 
HORN EXPEDITION—MOLLUSCA. 
The majol’ diameter of the umbilicus of the planulate forms bears to the 
greatest width of the base, the proportions varying from 1 : 4T to 1 : 4’8 
(averaging 1 : 4‘3). In the type the measures are 1 to 5, and with increasing 
height of the spire the umbilicus becomes smaller. 
4th. Summary of Varietal Characters. —Without attaching any undue value 
to the characters about to be utilised, it may be convenient to view tlie species as 
comprising the following groups ;— 
Forma typica, in which the spire is about seven-tenths in length of the 
major diameter of the base, the transverse ridges feebly developed, and the 
umbilicus of moderate dimensions. 
Forma a. —Spii’e and umbilicus as in forma tyfica, the transver.se ridges 
conspicuously elevated and usually fewer in number. 
Forma b. —Spire about five-tenths the major diameter of the base; peristome 
nearly complete ; aperture oboval, and the umbilicus large. 
Of the many dozen specimens which I have collected of this composite species 
forma b is the least frequent, forma a the most common, whilst the type-form is 
most commonly I’epresented by individuals of the largest dimensions. 
Forma b makes a connection with T. clydonigera, Tate, and through that 
species with T. silveri, Angas. The acute ridges are from 50 to 60 in number on 
the posterior part of the last whorl, but become finer and about double in number 
on the base. 
Thepsites (Badistes) pepinflata, Pfeiffer. 
Helix perinjlata., Pfeifier, Pro. Zool. Soc., 1863, p. 528 ; id., Cox, Aust. 
Landshells, p. 45, pi. xx., fig. 2, 1868 ; id., Hedley, Proc. Hoy. Soc. Queensl., 
vol. vi., pi. XV. (anatomy), p. 251, 1889. 
Hadra perinflata (Pfr.), Pilsbry, Man. Conch., ii., vol. vi., p. 183. 
Helix (Galaxias) perinflata (Pfr.), Bednall, Trans. Roy. Soc. S. Aust., vol. 
xvi., p. 62, pi. i., fig. 6, 1892. 
H. pachystyloides, Cox = H. jannellei, Le Guille, was considered by Angas, 
Quart. Journ. Conch., vol. i., p. 135, 1876, to be identical with the McDonnell 
Range species, a determination unanimously rejected. 
