A REVISION OF THE BRITISH IDOTELD^E. 745 



shortened basal segment and the elongated outer lobe of the latter appendages. In 

 I. viridis these two parts are about equal in length, and the coxal plates do not form 

 the complete lateral margin of the second to fourth mesosomatic segments, as in this 

 species. The posterior margin of the terminal segment of the metasome in /. viridis 

 is not laterally truncate, whilst the endopodites of the uropoda are broader and more 

 truncate in that species than in this. 



It gives me great pleasure to associate with this species the name of Professor 

 G. 0. Sars, to whom I am indebted for many interesting species of this family. 



(7) Idotea viridis (Slabber). (PI. VII, figs. 70-80.) 



Oniscus viridis, Slabber, Naturk. verlustigingen, 1778, p. 104, pi. xii, figs. 4, 5. 



Idotea plioyhorea, Hoek (nee Harger), Crust. Neerlandica, 1889, ii, p. 7, pi. vii, fig. 2, 2r. 



Idotea salinarum, Dollfus, Feuille des jeunes Nat., 1895, p. 7, fig. 21. 



Idothea viridis, G. 0. Sars, Crust. None, 1897, ii, p. 83, pi. xxxiv, fig. 2. 



Idothea angusta, G. O. Sars, ibid., p. 84. 



Idotea viridis, Norman, Ann. and Mag. Nat. Hist., 1904 (s. 7), xiv, p. 442. 



Body oblong linear, somewhat depressed. Cephalon (fig. 70) wider than long, 

 anterior and posterior margins slightly emarginate. Eyes moderate in size, situated 

 dorso-laterally. Antennuke (fig. 71), first joint only very slightly expanded, second 

 and third elongated ; fiagellum with single clavate joint. Antennae (figs. 72 and 73) 

 slender, fourth and fifth joints subequal ; fiagellum with twelve joints, mostly 

 elongated, style conical with long sete. First maxillae (fig. 74), outer lobe narrowed 

 distally, with six stout curved spines and three toothed ones. The segments of the 

 mesosome (fig. 78) are somewhat unequal in length, pleural plates of the first with 

 rounded anterior and posterior angles. Coxal plates of the second to fourth segments 

 narrow and not occupying the whole of the lateral margin, those of the fifth and 

 seventh segments much wider and occupying the whole of the lateral margins. 

 Maxillipedes (fig. 75) elongated, palp four-jointed, basal plate narrowed on the inner 

 side, epipodite oblong oval, distal inner lobe fairly large. Thoracic appendages (figs. 76 

 and 77) much more slender than in most other species, and elongated. Metasome 

 (fig. 79) with two short segments and well-marked lateral sutures indicating a further 

 coalesced one, terminal segment slightly convex, lateral margins almost parallel, 

 narrowing a little towards the posterior end, posterior margin terminating as a 

 drawn-out point, with obtuse lateral corners. Uropoda (fig. 80) narrow, endopodite 

 obtusely truncated terminally, outer margin cut away, setose style normal. 



Length of ^ 12 mm., of $ 10 mm. 



Colour greenish or greenish-yellow. 



Geographical Distribution. — St Andrews Bay and Isle of Wight ; St Kilda 

 (Hewitt) ; Clyde Area (Patience) ; Suffolk coast, Weymouth, and Guernsey (Norman) ; 

 South and West Ireland (Tattersall) : also Norwegian coast (G. O. Sars) ; coasts of 

 Holland and France (Hoek). * 



Remarks. — This species must be considered rare in St Andrews Bay. Thanks to 



TRANS. ROY. SOU. EDIN., VOL. LI, PART III (NO. 23). 109 



