THE NEMERTINES OF MILLPORT AND ITS VICINITY. 9 
eyes, and may appear bluish-red, dusky purple, or even black. MacInrosn apparently 
did not meet with these forms. 
MaclInrosu gives the length of his specimens as three to four inches (approximately 
75-100 mm.); JouBIN gives 600 mm. as the maximum for C. linearis, and says that 
C. bioculata is shorter than C. linearis; BURGER makes C. linearis 100-150 mm., and 
C. rufifrons ( = bioculata) only 30-40 mm.; my specimens were 50-75 mm., on the whole 
somewhat shorter than MaclInrosu’s and intermediate between BURcGER’s two forms. 
If now it is decided to separate these forms into two species, this may conceivably 
be done either on the basis of the presence or absence of a red tip to the snout, or on the 
ageregation or otherwise of the bluish granules into eyelike masses. The presence of the 
first of these characters is the origin of the appellation rufifrons, the second of broculata. 
The latter of the indicated alternatives is the one chosen by Btrcer in the 
Trerreich. The diagnosis of C. linearis runs: ‘‘ Weiss ofters mit gelblichem Anfluge. 
Ohne Pigmentflecke. L. 100-150 (nach Joubin bis 600); Br. 0°5-1 mm.” That of 
C. rufifrons is: “ Weisslich. Mit 2 kleinen rot-blauen Pigmentflecken an der Kopf- 
spitze. L. 30-40, Br. 0°5 mm.” 
On this it may be remarked that the reddish-blue spots are variable features, 
consisting as they do apparently of closer or looser aggregations of scattered granules. 
Their size seems to vary, and also their colour, the latter feature probably according to 
the closeness of the aggregation ; their position, too, is not always the same, for while 
JouBIN describes them as on the extreme margin, I have always found them a little 
distance within the margin ; their number also varies—sometimes three, sometimes only 
two. Again, if this feature be adopted as the criterion, the Millport specimen (b) above 
(which for the rest comes nearest of any of my specimens to BURGER’s Naples specimens 
of C. bioculata with two small bright red spots) would have to be excluded from C. 
rufifrons as showing no trace of a blue tinge; while all my others, though with a less 
concentrated pigmentation, would nevertheless be C. rufifrons. 
Burcer himself gives us an example of the confusion which results from taking 
this character as a criterion. As we have seen, he considers his Naples specimens (C. 
broculata, = C. rufifrons of the Tierreich) to be the same form as MacINTosH’s specimens 
with red pigmentation. MacInros groups all his forms together as C. linearvs, and 
accordingly we find in the Tierreich, as part of the synonymy of C. rufifrons, 
“C. linearis (part.) MacInrosx.” It may, however, be inferred with certainty that 
Maclwrosu’s specimens had no red-blue pigment spots, since they could not possibly 
have escaped his observation if present (he states, indeed, that there are no eyes); yet 
this is the character which to BURGER is distinctive of C. rufifrons, under which he 
subsumes these specimens of MacInrosn’s. 
If the presence or absence of red-blue pigment spots fails as a criterion of distinction, 
much the same kind of objections seem to apply to the presence or absence of a red tip 
to the snout. The extent of pigmentation may be greater (MacInrosuH) or less (Mill- 
port forms, Naples forms) ; it may be delimited in two patches (BURGER), or continuous 
TRANS, ROY, SOC, EDIN., VOL. XLVIII, PART I. (NO. 1). 2 
