290 TAYLOR : VARIATION OF LIMN^A PE-REGRA. 



in describing the var. stnistrorsa, gives the shell as spirally 

 ridged, but it is evident in this case — as in many other parallel 

 cases which could be adduced — that the spiral sculpture is 

 what I have termed an individual peculiarity and not necessarily 

 present in sinistrally coiled specimens. 



In the present paper I propose to divide the form- 

 variations into two groups or sections, under which I shall 

 give faithful and accurate outlines of the various modifications 

 of shape that have received definite names, characterizing the 

 groups by the relative lengths of the aperture and spire, 

 and the proportion they bear to the length of the whole shell. 



SECTION' A. 

 Spire short and aferhire exceeding threc-fonrths of the total length of 



the shell. 



Var. burnetti Alder. Shell globose, ra'.her solid, of a dull dark horn- 

 colour, epidermis rather thick, strongly striate in line 

 of growth, spire scarcely elevated beyond the body- 

 whoil, apex intorted. 



This remarkable variety, which is apparently 

 confined to the British Isles, has only been found 

 well characterized in the original locality. Loch 

 Skene, Dumfriesshire. Dr. Jeffreys has, however, recorded it 

 from a Welsh lake called Llyn-y-van-fach, and as having been 

 taken from the stomach of a gillaroo trout caught in a lake in 

 Tipperary. Tate is the only author I am aware of who, in 

 addition to the original locality, states that it is also found 'in 

 a few other Scottish lakes.' 



Specimens collected by Mr. F. W. Wotton, and Mr. 

 J. Madison from the Welsh locality, do not fully exhibit the 

 peculiarities of this form, and would seem to link this variety 

 with the var. lacustris of Leach. 



Westerlund treats this form as a distinct species, placing it 

 in his arrangement between Z. ovata and Z, peregra, 



J,C,, vi., Jan., 1891, 



