Gatty Marine Laboratory, St. Andrews. 171 
from Greenland and Canada (P. minuta, Fabr.), compara- 
tively little difference is observed, both having from 18 to 23 
moniliform cilia externally. 
The posterior scales in var. ¢nornata become still more 
elongated transversely, have only about 6 of the larger 
moniliform cilia on the abbreviated external border as well as 
the posterior edge. 
On the whole, therefore, the study of the scales supports 
the view that P. ménuta, Fabr., and Dr. Johnston’s P. énornata 
are the same species. 
In the variety ewimia of Dr. Johnston the first pair of 
scales are similar in shape to the foregoing, though from the 
smaller size of the examples they are considerably less. The 
outer border has a series of longer cilia, fewer in number, but 
similar in structure. They encroach somewhat on the ante- 
rior border, or, rather, a few of the isolated cilia scattered 
over the surface project beyond the edge. None of the 
smaller clavate cilia so characteristic of the two foregoing 
varieties are present on this edge. The large isolated cilia 
occur both externally and posteriorly to the scar for the 
elytrophore. ‘The second pair of scales are distinguished by 
the greater length of the cilia on the outer border. A few 
also occur along the posterior edge. 
The succeeding scales of the anterior third do not differ 
much in shape from those of P. mznuta, but the cilia are 
much longer and stand stiffly out on the external margin and 
the outer half of the posterior edge. They are less numerous 
than in the large examples of P. cnornata, but agree with the 
smaller in this respect. The posterior scales have abont the 
same number of cilia as P. tnornata, but they are stiffer and 
longer. JP. eximia is distinguished externally from P. ¢n- 
ornata in spirit by the olive spot with a pale centre in each 
scale at the scar for the elytrophore. Occasionally in certain 
forms of eximia, e. g. from Lochmaddy, North Uist, the cilia 
on the scales are fewer, longer, and without the terminal 
enlargement. 
The second foot (first bristled) in P. cnornata is bifid, with 
two well-developed spines. ‘The dorsal lobe forms a rounded 
eminence with a smooth surface, from which project the com- 
paratively short, slender, minutely spinous bristles, with a 
very fine hair-like tip. ‘The inner forms taper more abruptly 
than the outer, and the tips are often bent nearly at right 
angles to the base. The ventral lobe is longer, bluntly 
conical, and with numerous small papilla on its surface. The 
ventral bristles have stout shafts, dilated at the tip, and with 
numerous rows of spines on the convex margin, thus differing 
