on the Coast of' Scotland. 297 
tryman, instead of employing the term of our English naturalist, 
which had been first established. There is, however, no neces- 
sity for the extinction of either genus, as there are characters 
peculiar to each of the species which have been regarded as 
types, overlooked byaboth Latreille and Lamarck. In the Lep- 
tomera, the tarsi of the second pair of feet only are furnished 
with a moveable claw ; while in Proto, all the feet are unguU 
culated. In the latter genus, the second, third, and fourth pairs 
of feet have appendages at the base, which are wanting in Lep- 
tomera. We are not aware that the Leptomera ventricosa has 
ever been detected on the British shores. 
In the Caprella, the other genus of the family to which Proto 
and Leptomera belong, there is only one species which has been 
distinctly ascertained as an inhabitant of our seas, viz. Cancel* 
Phasma of Montagu (Lin. Trans, vii. p. 66. Tab. vi. Fig. 3.), 
which he observed on the south coast of Devonshire. In 1817 
I found it at the Isle of May. It is subject to considerable va*- 
riation in the number and position of the spines, and the hairi- 
ness of the different parts. In the example now before us, the 
claw and last joint of the first pair of feet were deeply serrated . 
It is probable that the Caprella Pennantii , and acanthifera of 
Dr Leach (Edin. Encyclopaedia, vol. vii. p. 404.), are merely 
varieties of this species. In the bottom of a pool I observed the 
beautiful Planaria atomata of Muller (Zool. Dan. xxxii. 
Fig. 3, 4.), a species which I had previously noticed in Au- 
gust 1814 at Aberbrothick, on the neighbouring coast. This 
species, together with Planaria tremellaris of Muller (Zool. 
Dan. Tab. xxxii. Fig. 1- 2.), and P. vittata of Montagu (Lin. 
Trans, xi. p. 25. Tab. v. Fig. 3.), form a curious group of ma- 
rine Planariae, distinguished by their shape, ai\d the number 
and position of the eyes. 
Having returned from the Bell Rock to the vessel, the course 
of which was now directed to Aberdeen Bay, which was reached 
in the evening, I devoted some time to the examination of the 
molluscous cargo which I had brought on board. While ob- 
serving the motions of some of the animals in a glass of sea- 
water, a medusa presented itself belonging to the genus Gery- 
onia of Peron and Lesueur. The body was diaphanous, round 
at the margin, subconical, blunt at the summit, and slightly acu- 
