276 DR THOMAS SCOTT ON THE 



freely in the open sea. Such free-swimming species are subject to dispersal over wide 

 areas by tidal and other currents, and numerous examples of such dispersal are indicated 

 or described by various authors ; but the wide distribution of an Harpactid such, for 

 example, as Orthopsyllus linearis, Claus, may not be so easily explained. This Copepod 

 is one of a group which have an elongated and moderately slender body, provided with 

 short appendages that are scarcely, if at all, fitted for swimming, but are rather adapted 

 for living among branching zoophytes or on the roots and stems of seaweeds. The 

 transporting action of currents can have much less effective influence on the distribution 

 of such species than on species living a free life in the open sea. Nevertheless, 

 Orthopsyllus linearis has been recorded from the British Islands, from Norway, the 

 Mediterranean, the Suez Canal, the Gulf of Manaar, and the Gulf of Guinea. More 

 recently it has been obtained in material collected in the Malay Archipelago during the 

 Siboga Expedition of 1899-1902,* and now this non-swimming species is here recorded 

 from gatherings collected by the Scotia among the South Orkney Islands. 



Another species — Asterocheres suberites, Giesbrecht; — belonging to a different group 

 of Copepods, is usually found living as a commensal in the water passages of certain 

 sponges, t 



The wide dispersal of this Asterocheres cannot, from its peculiar habitat, be to any 

 large extent attributed to oceanic currents, yet it has been recorded from the British 

 Islands and the Mediterranean ; and one or two specimens from a gathering collected 

 among the South Orkneys by the Scotia can scarcely be distinguished from those 

 living on British sponges. Other species equally interesting and showing the near 

 relationship of the non-pelagic Copepoda of the far South with those of our Northern 

 Seas will be noticed in the sequel, but two may be briefly referred to here. One of them 

 — an Harpactid, obtained in a small gathering of minute MoUuscan shells collected on 

 the shore at Port Stanley, Falkland Islands — has a remarkable likeness to a species that 

 was dredged in the Firth of Forth off St Monance in 1891,j and which has been 

 described more recently by G. 0. Sars from Norwegian specimens. § The female of this 

 species is distinguished by having the last pair of thoracic legs large and leaf-like, — 

 hence the generic name Phyllojwdojysyllus. The other form is also interesting because it 

 may be regarded as supplying a " missing link " in the little group of nearly related 

 species representing four genera, viz. — Cervinia, Norman, Cerviniopsis , G. 0. Sars, 

 Zosime, Boeck, and Pseudozosime, Scott. In the first genus the inner ramus of the first 

 pair of thoracic legs is three-jointed and that of the next three pairs two-jointed ; in the 

 second all the four pairs of thoracic legs have the inner ramus three-jointed. In the 

 third the inner ramus of the first pair is two-jointed, and that of the next three pairs 

 three-jointed ; while in Pseudozosime the inner ramus of all the four pairs is composed of 



* The Copepoda of the "Siboga" Expedition, by Andrew Scott, A.L.S., p. 225 (1909). 



+ Fau7ia u. Flora des Golfes von Neapel, 25. Monogr., "Asterocberiden," by Dr W. Giesbrecht, p. 70. 



J Tenth Annual Report of the Fishery Board for Scotland, part iii. p. 253, pi. ix. figs. 19-32. 



S5 An Account of the Criistacea of Norway, vol. v. part xix. (1907), p. 231, pi. civ. 



(rot. soc. edin. trans., vol. xlviii., 522.) 



