of tlie Fishery Board for Scotland. • 231 



recorded as British by Conrad. Beck in the Journal of the Microscopical 

 Society for December 1883, and is there described and figured. Herrick, 

 in Crustacea of Minnesota (1884), states that it 'is not yet recognised in 

 ' Minnesota, but was found by Professor Birge in Lake Michigan.' 



Latona is distinguished from other British Cladocera by, among other 

 characters, the structure of the posterior antennas. The inner branches of 

 these appendages are two-jointed ; the distal portion of the basal joint next 

 the outer branch, is continued forwards in a leaf-like process to fully half the 

 length of the second joint, as shown in the figure. The Loch Morar 

 specimens were small — under 1 mm. — but the size appears to vary. 

 Mr Conrad Beck states that specimens 2*5 mm. (x^-th of an inch) ate 

 often obtained.* 



Family Holopedid.e. 



Cenus Holojiedium, Zaddach. 



Holoj/edium gibber urn (Zaddach). 



1855. Holopedium qibberum, Zaddach, Wiegman's Archiv. fiir 

 Naturges., Bd. xxi. p. 159, PL VIII. fig. 9. 



This remarkable species was common in Loch Morar, and especially so 

 near the surface of the water. It appears to be widely, but perhaps not 

 generally, distributed. In the Fishery Board's Ninth Annual Eeport 

 there are records of its occurrence in Loch Ness, Loch Oich, and Loch 

 Lochy, Inverness-shire. It is distinguished by the greatly elevated and 

 hood-like form of the brood-pouch. They frequently measure over an 

 eighth of an inch from the apex of the brood-pouch to the under side of 

 the body. When seen adhering to the tow-net after being removed from 

 the water, they closely resemble at first sight the little medusiform gono- 

 phores sometimes so abundant in the sea. 



Family DAPHNiDiE. 



It is noteworthy that no. species belonging to this family were obtained 

 in Loch Morar at the time of our visit. 



Family Bosminid.e. 



Genus Bosmina, Baird. 



Bosmina lovrjispina, Leydig. 



1SG0. Bosmina longispina, Leydig. 



This species was very abundant in Loch Morar. It is readily dis- 

 tinguished from Bosmina longirostris by its much greater size and by 

 the larger postero-ventral spine-like processes of the carapace. 



Family Macrothricid.e. 

 Genus Macrothrix, Baird. 



Macrothrix laticornis (Jnrine). ; (PI. VII. figs. 28, 29.) 



1820. Monoculus laiicoruis, Jnrine, Hist, des Monocles, p. 151, 



PL XV. figs. 6, 7. 

 1850. Macrothrix laticornis, Baird, Brit. Entom., p. 103, PI. 

 XV. tig. 2. 



* C. Beck, o}\ cit,, p. 7S?. 



