24 THE INDIGENOUS FAUNA. 



more diverse microtrema and depressa. In the original description 

 of T. prcelonga and microtrema it will be found that their different 

 microscopic shell-characters are much insisted upon as serving to 

 separate these two species from one another; the shell tubules in 

 the latter species being much smaller than usual, whence the 

 specific name was given: but as with the other characters so here, 

 there is every intermediate variety, and indeed I find both types 

 of structure in the same shell. Thus every character fails in an 

 attempt to find definite and unvarying points of distinction between 

 the several species. 



The appended Table is the result of the same kind of work 

 amongst the long-looped genus : 



WALDHEIMIA. 

 Waldheimia celtica (Morris) 



Wanklyni, var. angusta (Walker) 



Wanklyni, var. elliptica (Walker) 



I 



faba (d'Orb.) (?) 



pseudojurensis (Leym.) "many varieties -new species 



(Hughesii Kpng.) 



tamarindus (Sow.) 



Juddii (Walker). 



In this table all is plain sailing from W. celtica through the 

 forms of Wanklyni to the flattened varieties of pseudojurensis, and 

 no one will dispute the continuity of the series through the 

 many varieties of the last-named species, with digonal and elon- 

 gate forms, inflated and rounded, or thin and flattened, and in- 

 cluding the new type, W. Hughesii (Keeping). From this point 

 the chain of passage to Waldheimia tamarindus is somewhat 

 strained, and is perhaps not really true in nature, but from the 

 latter species we pass on again without break or difficulty to 

 arrive at Waldheimia Juddii (Walker). 



The Waldheimia Woodwardi (Walker) remains isolated, belong- 



