24 A MONOGRAPH OF 



36. — Helix ( ) Diemenensis — Cox. 



Mon., 1868, p. 20, pi. vii., fig. 6, 6a. 

 Pro. Zool. Soc, 1867. 

 Legrand's Col. for Mon., sp. 3. 



H. Wellingtonensis — Cox. 



Mon., 1868, p. 29, pi. vii., fig 5, 5a. 

 Pro. Zool. Soc, 1867 

 Legrand's Col. for Mon. sp. 15. 



H. Daveyensis — Cox 

 H. Athinsoni — Cox. 

 H. ThoTTipsoni — Cox. 

 JT. CamillcE — Cox. 



Legrand's Col. for Mon., sp. 35. 

 Legrand's Col. for Mon., sp. 62. 

 Legrand's Col. for Mon., sp. 73. 

 Legrand's Col. for Mon., sp. 74. 



Shell umbilicated, depressly-orbicular, sub-discoid, thin, with thread- 

 like riblets radiating sub-arcnately, frequently extending even to its 

 umbilicus, scarcely shining, varying in colour from glassy white to dirty 

 yellow, and more or less rayed with chestnut ; spire small, a little ele- 

 vated, sometimes fiat ; whorls 5 to b^, slowly increasing, moderately 

 convex, last more convex, not descending in front ; umbilicus perspec- 

 tive, equalling one-third oi the diameter, steep, and often angled at its 

 opening j aperture moderately oblique, lunate ; peristome simple, thin, 

 straight ; margins approaching ; columellar margin neither dilated nor 

 reflexed. 



Diameter, greatest 0*27, least 0*23 ; height, 0-14 of an inch. 



Variety a. — Chestnut colour throughout, the H. Daveyensis — Cox. 



Variety h. — Glassy-white throughout, the H. Wellingtonensis — Cox. 



Variety c. — Pure white, without rays of colour. 



Habitat. — Widely distributed, also islands in Bass Straits. 



I have no hesitation in uniting the six species (f) that Dr. Cox has 

 formed of this somewhat varying shell, whose principal differences were 

 that they came from various parts of the colony. The specimens named 

 respectively Daveyensis and Wellingtonensis are but variations in colour; 

 that named Atkinsoni stunted in growth ; but the difference separating 

 those named Thomi^soni and carnillcB from the typical form is totally 

 beyond my comprehension. I have examined some thousands of speci- 

 mens from all parts of the island, and also from the majority of the 

 islands in Bass Straits, and I am thoroughly convinced that they are 

 but very slight variations of one common form generally distributed ; in 

 fact, from those I have collected around Launceston it is possible to 

 assign picked specimens to any of the species (?), and find intermediate 

 variations one to another. The number of species might be extended ad 

 libitum if such slight variations in colour or form are to be considered ot 

 specific value. The radiate bands of chestnut are as often absent as 



