Triehoniscoides albidus and T. sarsi. 87 



I submitted the matter. In forty-eight male specimens of 

 T. albidus and seven male specimens of T. sarsi which I 

 carefully dissected and examined the form and structure of 

 the first and second pairs of pleopoda were constant, with one 

 exception, in T. albidus, where the right opercular plate of 

 the first pair of pleopoda was abnormal, only to the extent, 

 however, of having three equal-sized lashes instead of the 

 usual two. The structure of the seventh peroeopod of the 

 male in both species I also found to be constant in the above 

 number of specimens examined. 



Quite recently my friend Mr. It. S. Bagnall, F.E.S., 

 Winlaton-on-Tyne, submitted to me for examination a 

 number of specimens of T. albidus taken in the Kew Gardens, 

 London, and at Newcastle-on-Tyne respectively. All the 

 males exhibited, in the organs under consideration, the same 

 kind of structure as was found in the Scottish examples. Of 

 the other British species of the Trichoniscidse which I have 

 examined, e. g. Trichoniscus pygmceus, G. O. Sars, T. steb- 

 bingi, Patience, T. spinosus, Patience, and Haplophthalmus 

 danicus, Budde-Lund, I have found the structure of the first 

 and second pairs of pleopoda of the male to be virtually 

 constant in each species. 



Occurrence. I have met with T. albidus in many localities 

 in the Clyde faunal area, from Stonebyres Falls, near Lanark, 

 to as far south as Largs, on the Ayrshire coast, and in one 

 or two places in fairly extensive colonies. It may be inter- 

 esting to note that I have rarely found it far away from the 

 river-bank or the sea-beach line. On the south bank of the 

 river Clyde, opposite Bowling, where I found it associated 

 with Haplophthalmus mengii (Zaddach) and Trichoniscus 

 pygmceus, G. O. Sars, the stones under which it lives are 

 almost lapped by the water at high tide, and on Hailie shore 

 to the south of Largs it is within splash of the waves. It 

 also occurs in the Island of Bute, being one of the species I 

 found in Dr. Marshall's garden at Battery Place, Rothesay. 

 On the eastern side of the Firth of Clyde, from Ashton to 

 Fairlie, there are many green patches fringing the shore 

 just close to high-water mark, and there I have found the 

 following members of the Trichoniscidas to be not un- 

 common: — Trichoniscus pusillus (Brandt), T. pusittus, var. 

 viulaceus, T. pygmceus, G. O. Sars, T. roseus (Koch), and 

 Haplophthalmus danicus, Budde-Lund. Apart from the 

 English localities mentioned above, T. albidus has also been 

 taken at Eton and Sunderland*? 



* ' The British Woodlice,' p. 26. 



