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the distinction being in the height the terga rises above the scuta. But 

 from the wearing received, not only will this character be found highly 

 variable, but also other external characters relied on in the classification, 

 including (a) the size of the rostrum and its projection, (b) the projection 

 of the carinal apex, (c) the size of the valves and the number of lateral plates 

 developed. Taking this into account, I could see no valid distinction be- 

 tween the specimens labelled by Hutton P. spinosus and P. darwini, when 

 placed side by side. 



But there were in my original collection, and I found others by careful 

 search in the rocks, a few specimens from sheltered positions with the 



Fig. 3a. — Pollicipes darwini Hutton. Type specimen, dry and worn. Diagram 



showing shape and position of plates. Height of specimen, 27 mm. ; 



width, 19 mm. 

 Fig. 36. — Pollicipes sp. Well-preserved immature form, with the characters of 



P. sertus. Height, 19mm.; width, 13mm. 1, Rostrum; 2, left 



scutum ; 3, left tergum ; 4, carina ; 5, subcarina. 



points of the valves and plates sharp and the surfaces uncorroded. They 

 are mostly immature, but there is an occasional full-sized one. If these 

 were examined independently they would certain be classed as P. sertus. 

 They have the distinctly projecting rostrum and carinal apex. I have 

 figured one in fig. 3b. They are found amongst the very common worn 

 specimens which, I have not the slightest hesitation in stating, after 

 examining his type and visiting the locality where he obtained them, are 

 what Hutton meant to distinguish as P. darwini. 



Yet, beginning with these well-preserved forms, can be found practically 

 all stages leading by growth and wearing into the common form. 



I am practically convinced that there is only one species in all these 

 New Zealand Pollicipes, whose external characters get highy modified by 

 wearing ; that it is the young and well-preserved forms of it which have 

 been called P. sertus ; that the somewhat worn specimens, with therefore a 

 shorter and wider rostrum, apex of carina not projecting, apex of terga 

 not rising much above apex of scuta, and a good showing of lateral plates 

 and spines, are those which have been called P. spinosus ; and that the 



