1904-5.] Free- Swimming Crustacea of Firth of Clyde. 
801 
only time it was observed. It differs from its nearest allies in 
being truly pelagic in its habits, and is at times moderately common 
in the open sea. 
Tegastes falcata, Norman (No. 24), is the species that has 
frequently been described as Amymone sphcerica, Claus ; but Rev. 
Canon Norman has shown,* however, that the generic name 
Amymone is preoccupied, and that the species is his Amymone falcata, 
described in 1868. f A single specimen of this curious form was 
observed in a plankton sample collected on 9th December. 
Ameira longicaudata 
Laophonte horrida 
Diosaccus tenuicornis 
\Dadylopusia tisboides 
, , Stromi 
,, similis 
„ brevicornis 
The three species of Thalestris, as well as the Harpadicus and 
Westwoodia mentioned in Table II. (Nos. 32-38), are all of them 
bottom forms, and are more or less frequent amongst the roots of 
Algae and Zoophytes within the laminarian and littoral zones. 
They are all very sparingly represented in the present collection. 
Tigriopus (. Harpadicus ) fulvus (Fischer) and Porcellidium 
fimbriatum, Claus, are each represented in the • collection by a 
single specimen. The Tigriopus was observed in one of the 
December gatherings, and the Porcellidium in one of those collected 
in October. The first is sometimes not uncommon in shore pools 
even above high-water mark, and the other is frequent on the 
fronds of Laminaria and other sea-weeds, on the surface of which 
it can run quickly and adhere firmly when alarmed. 
Tisbe (or Idya) fur cata, longicornis, cluthce and minor, though 
not so free swimmers as some of the Calanoids, they all appear to 
have, to a certain extent, adopted pelagic habits, as they are 
frequently found in tow-net gatherings collected near the bottom. 
Tisbe cluthce, which has only hitherto been observed in such 
* Ann. and Mag. Nat. Hist. (7), vol. xi. p. 368 (April 1903). 
t Brit. Assoc. Report for 1868 (pub. 1869), p. 296. 
X Canon Norman points out (Ann. and Mag., April 1893) that, as 
Dactylopus is preoccupied, he has substituted Dadylopusia for it. 
PROC. ROY. SOC. EDIN. — VOL. XXV. 51 
These are all demersal in their 
habits, and are therefore more fre- 
• quently obtained by the dredge than 
the tow-net. They only occurred at a 
few odd times throughout the year. 
