162 ANNALS OF SCOTTISH NATURAL HISTORY 



central setae on the discs, tendency to spines or tubercles 

 on trunk, and above all in being viviparous. Another 

 group of four-toed Bdelloids of possibly generic value would 

 include Callidina alpiuni, C. Brycei, and one or two others, 

 which have distinct transverse folds on the ventral surface 

 of the trunk, those folds being more numerous than the 

 divisions of the segments. These species also have the four 

 toes arranged in a different manner from the other four- 

 toed Bdelloids, the dorsal being the larger pair. Further 

 notes on the affinities of the species will be given in the list 

 which follows. 



This list includes only species which I have myself 

 identified, or which Mr. Bryce has named from my drawings 

 or found in material sent to him. There was neither time 

 nor opportunity to compile a list of published records. If 

 the species recorded by Hood, Milne, Bryce, and others were 

 added, as well as a number of new species recently found in 

 the course of the work of the Lake Survey and yet unde- 

 scribed, the list would be nearly doubled. 



ORDER BDELLOIDA. 

 Family ADINETAD^E. 



Adineta vaga, Davis. Both the varieties major and minor, recognised 

 by Mr. Bryce, are common among Sphagnum. Blantyre Moor. 



A. barbata, Janson. A large species, with prominent rostral styles, 

 resembling the antennae of insects. The large symmetrical egg 

 is covered with rounded bosses. Frequent, Blantyre Moor, 

 Inverness-shire. 



A. gracilis, Janson. Small and slender, and excessively active, 

 even for this genus. Frequent, Loudoun Hill, Rannoch Moor, 

 Inverness-shire. 



Family 



Philodina macrostyla, Ehr. Very common, and extremely variable 

 in size. The tubercled variety (P. tuberculata, Gosse) is probably 

 only a state in which the secretion of mucus is excessive. The 

 secretion takes the form of plates crowning the longitudinal 

 dorsal folds of the trunk and interrupted at the junctions of 

 the segments. In extreme cases the projection of those plates 

 will about equal the diameter of the extended trunk. This 

 and the next species are the only viviparous Philodina? with 

 which I am acquainted. 



