8 DR J. STEPHENSON ON 
these forms into one, or their separation into two, species depends mainly on the facts 
of pigmentation, a full account of this character and its variations will be given. 
The general colour of most of my specimens was yellow; in some cases it was a pale 
orange, deeper in tint in the anterior part of the body. In all cases the anterior tip 
of the head was brilliantly coloured, either a bright orange or a bright red; this area of 
colour was not definitely limited, but was smaller im extent than that shown in 
MaclIntosn’s pl. iv., fig. 5. The red pigment appeared to be partly diffuse and partly 
or mostly granular, and the individual grains had a bluish tinge ; two larger agerega- 
tions, symmetrically placed one on each side, near the anterior end and near, but not 
at, the margin of the body, resembled two eyes; a somewhat smaller and more 
anteriorly placed median spot was also sometimes distinguishable ; and, by focussing, 
it was found in one instance that the lateral spots were dorsal, the median spot, how- 
ever, ventral. 
In addition to the above general account, two observations may be given in detail; 
both the following specimens were obtained from Fairlie, on the mainland. 
(a) In one of these specimens the pigment in the head consisted of (1.) an orange 
pigment, diffused (7.e. not ageregated into visible granules) over the anterior end of 
the head, continuous in area, not as two patches; (ii.) a granular pinkish-red, with a 
slight blue tinge, at the tip of the head, apparently between the epithelium and the 
deeper layers, much more limited in extent than the orange ; (ii1.) two large dark spots, 
of a dusky purple colour, one on each side near the anterior tip, but no median spot. 
(b) The second specimen contained ripe ova; the whole anterior part of the body 
was more orange than usual, and this was especially marked over the anterior part of 
the head and over the cesophageal region. In this case the distinctive pigment at the 
anterior tip was mainly concentrated into two red patches, with an especially brilliant red 
spot in each; there were no blue eye-like spots at all. There were also over the general 
surface of the body, but not of the head, a large number of minute white specks. 
It follows from the above descriptions taken together that forms are met with in 
colour from whitish through cream to yellow and pale orange; that the anterior end of 
the body is in many specimens more deeply pigmented than the rest; and that in a 
whole group of forms the extreme tip of the snout has a brilliant red or orange colour. 
Again, in the specimens with red tip, the red colour may be more or less extensive 
and more or less definitely localised. MacInrosH evidently considers it as an intensi- 
fication of the body-pigment, and shows it as of relatively considerable extent; JouBIN 
also indicates that it is not delimited from the general red colour of the head; my own 
specimens show a more limited extent of brilliant red than Maclnrosn’s, but equally 
with his and Jousin’s it is not sharply defined ; while BUrGEr, on the other hand, finds 
two very small bright red spots. 
Further, in these specimens with red tip, the pigment may be in part granular, and 
the granules may have a bluish tinge. Aggregations of these granules may be dis- 
tinguishable to the number of two or sometimes three; such aggregations look like 
