452 



W. F. LANCHESTER. 



This includes term b of this variety, and a certain number of the intermediates which 

 approach very closely to it, the carinae being a little less swollen in varying degrees, and 

 the spines generally absent. 



The forms described above may be arranged, as I have said before, in a transitional 

 scheme in such a way that, if we start, for convenience, from the tumidus-iorm, the rest 

 of the forms come to lie along two closely parallel lines (corresponding to the two headings 

 under which I have dealt with them), each of which may take the tumidus-iona as its 

 starting-point. This arrangement is sho^vn in the following table, and I have affixed letter- 

 symbols to each variety, in addition to the name-symbols, following on the line taken by 

 Mr Borradaile in Willey's Zoological Results, Pt. iv. where five varieties are described and 

 lettered from A to E; the first of my varieties, therefore, begins at F, while any varieties 

 referred to by the letters A — E are the same as those correspondingly lettered by 

 Mr Borradaile. The first column in the table forms a very perfect transition-series, but it 

 must not be supposed that the transitions are exactly of the same degree as between form 

 and form ; thus, though I have separated var. D into two parts for the purposes of this 

 transition-scheme, I should, had I been dealing with them by themselves, have treated them 

 as one variety; this fact is expressed by giving them the same varietal name. The distinction 

 between var. G and var. D is however definite, they are separated by a greater interval 

 than the two parts of var. D, and this fact is expressed in the difference of varietal 

 name. A similar situation arises in respect of the varieties in the second column in their 

 relation to those of the first column ; thus var. H in column 2, can scarcely be separated, 

 on structural grounds, from var. H in column 1, whereas the two forms of var. A in 

 column 2, though their structure requires them to occupy a similar position in column 2 

 to that which the two forms of var. D occupy in column 1, are still so far distinct from 

 the latter varieties as to require a different varietal name. 



This table then I arrange as follows : — 



var. D. 

 var. D. 

 var. H. 

 var. H. 

 var. I. 

 var. K. 

 var. L. 



: smithii a. 

 smithii b. 

 segregatus a. 

 segregatus b. 



glabrous (term a. and the inter- 

 mediates near it) 



= 7nutatus 



var. A. = incipiens a. 

 var. A. = incipiens h. 

 var. H. = segregatus c. 



var. \.=glahrous (term b. and the inter- 

 mediates near it) 



-graphurus 



