POLYCH ESTA FROM THE N.E. PACIFIC. 989 
more of the cusps are of greatly inereased size. The lower side 
of the crown is usually smooth or slightly crenulated. 
In P. anglica the set are often very similar to those of 
P. prolifica. Two sete are here figured to show the extent 
of the variation in number and size of cusps. In one of them 
(text-fig. 12, A) there are only two cusps, one of which is very 
large. In the other (text-fig. 12, B) the appearance of a cuspate 
lower border will be noticed. 
Text-figure 12. 
A B 
Phyllochetopterus anglica. 
Enlarged sete from 4th segment of two individuals, 
The figure which Crossland has given of P. pictus shows an 
enlarged seta of a type different from any which | have described 
for P. prolifica and anglica. In text-fig. 138, C, however, IT have 
drawn another seta from the 4th parapodium of a 2. pictus 
collected by Crossland, and I think, it will be seen to be easily 
derived from the seta shown in text-fig, 12, A (P. angliew). 
The cusps on the lower border are better developed in the first, 
but otherwise the two are strongly similar. ‘The bulging shaft 
of the seta mentioned by Grossland is shown also in my 
mounted specimen, but I ave observed similar phenomena in 
P. prolifiea. 
P. elioti is another species which from the published description 
appears to have a very definite type of strengthened seta. 1 
mounted two or three setz from Crossland’s specimen, and one of 
these (text-fig. 13, B) agreed fairly well with his figure. On the 
upper side the two external cusps are greatly enlarged, contrasting 
with the two small intermediate cusps (not seen at all in Cross- 
land’s figure), But another seta (text-fig. 13, A) showed an 
oblique crown with small equal cusps, like the usual type of 
P. prolifica ete. 
It is very probable that the average seta of a species is different 
