Contribution to Knowledge of Paleospondylus Gunni. 321 
Fig. 4. Anterior part of another head, magnified six diameters. The 
dorsal margin of the nasal ring with stumps of cirri is seen, but the ventral 
margin is broken through in the middle. 
Fig. 5. A head figured in my former paper (5, Pl. I., Fig. 2), but here 
magnified up to seven diameters. Only the ventral margin of the nasal ring 
is seen, with obscure traces of cirri externally on each side. In this specimen 
the surface of the skull is wonderfully entire and uneroded, but it seems just 
a little frayed along the margins. 
Fig. 6. Part of the tail of the specimen, the anterior part of whose head is 
represented in Fig. 4, to show the dichotomisation of the neural spinous 
processes, Magnified thirteen diameters. 
Fig. 7. The specimen, natural size, whose head is represented in Fig. 2. 
Fig. 8. Restored outline of Palaospondylus Gunnt, altered from the figure 
previously given (5, p. 90) in accordance with the present state of knowledge. 
XXIII. On some Fresh-Water Entomostraca from the Island 
of Mull, Argyllshire, collected by the late Mr George 
Brook. By Tuomas Scort, F.LS., Naturalist to the 
Fishery Board for Scotland. 
(Read 17th January 1894.) 
During the year 1890 the late Mr George Brook visited a 
number of small fresh-water lochs in the island of Mull, 
when several gatherings of invertebrates—chiefly Ento- 
mostraca—were collected and preserved. I happened to 
meet Mr Brook on one or two occasions afterwards, when he 
spoke of the collections he had made, and offered to hand 
them over to me for examination if I would arrange to send 
for them. Having at the time a good deal of other work on 
hand, I delayed doing so till there was some prospect of my 
being able to examine and describe them. Owing to the 
lamented death of Mr Brook last year, I had given up all 
thought of the collections, but a few months ago Mr Binnie 
—Mr Brook’s assistant—informed me that they were still 
intact, and that I could have them; and this explains how I 
have been able to prepare the following report. 
The collections having been carefully worked up, the 
report I now propose to lay before the Royal Physical 
Society contains a record of the results obtained. I have 
the more confidence in submitting this communication, 
