THE ROTIFERA OF THE SCOTTISH LOCHS. 171 
Philodina.—Toes four. There may or may not be eye-spots; when present, they 
are cervical. The genus is divided into three sections, denoted by the letters A, B, C. 
The first two are only for convenience ; the third is natural (except P. laticornis), and 
should perhaps form a separate genus. 
A. Oviparous, eyes cervical. 
B. Oviparous, eyes absent. 
C. Viviparous, eyes present or absent. 
P. brevipes, Murray. (Plate I. figs. 2a to 2c.) 
Though occasionally locally abundant, the species is uncertain in its occurrence. 
Its abundance in Loch Morar in 1903-4 enabled me to study it more fully than when 
the animal was first described (39), and better drawings were obtained, which are here 
reproduced. 
The straight setee on the rostrum are of extraordinary length, projecting at each side 
considerably beyond the sides of the head. There are thick tactile setae under each lamella 
(fig. 2b); it is uncertain whether there is a pair at each side, as there is in P. macrostyla. 
Seven pairs of vibratile tags were seen—at each side two in the head, on each branch 
of the forked canal, one pair in the first cervical segment, and four pairs in the central 
seoments. They are set at equal distances apart, but there is a gap im the series, or a 
wider interval, at the level of the mastax, or between the third and fourth tag at each 
side, counting from the front. This hiatus appeared in several individuals studied, so 
I hardly think the tags (which are conspicuous) have been overlooked. 
The foot is three-jointed, but there is often an appearance of four joints. In 
fig. 2c I show how this is brought about. Each telescopic segment of the foot of 
a Bdelloid consists of a somewhat firm cylinder. These are joined together by soft, 
flexible skin, which renders the telescoping possible. Where the soft skin joins the 
firmer cylinder there is often a little elevated ridge, more marked than usual in the 
present species. In the fullest extension of the foot this soft skin, with its limiting 
ridge, appears like an extra joint. 
In Loch Morar, in 1903, all the examples found had a hair-lhke growth on the head. 
Mr Bryce considers this hair as fungoid, and attributes to such a growth the P. hirsuta 
of various authors. It is dificult to understand the symmetry of the hair, and its 
confinement to the head. In P. laticeps, similarly affected, the growth was confined 
to the trunk. 
Differmg from P. citrina in many points, careful study is necessary to discriminate 
the two species. Less massive than P. eitrina, P. brevipes is also of quick, restless 
habits, very different from the elephantine deliberation of its relative. The marked 
characters of rostrum and foot are often ditticult to observe. The number of teeth is 
not a safe character, as P. brevipes has the usual 2+ 4/;+2, with the third tooth not 
infrequently as thick as the others. 
