458 Messrs. T. and A. Scott on some 



branches is considerably shorter than the first joint, being only 

 about two thirds the length of it ; the end-joint is also 

 narrower than the other ; both the branches of the first pair 

 are short and are of nearly equal length (fig. 4). The inner 

 branches of the next three pairs of swimming-feet, which are 

 also two-jointed, are very short, being not much longer than 

 the first joint of the outer branches ; the outer branches, on 

 the other hand, are elongate and robust, and consist of three 

 nearly equal joints, as shown by the drawing (fig. 4). In 

 the fifth pair the inner produced portion of the basal joint is 

 subcylindrical, rather longer than broad, and furnished with 

 four stout coarsely plumose seta and two smaller hairs, 

 arranged thus — the two small hairs are on the outer margin, 

 two of the larger plumose setse spring from the apex, and the 

 other two are subterminal, one on each side of the apical set?e : 

 the secondary joint is in form somewhat like that of the 

 produced part of the basal joint, but rather broader ; it is 

 furnished with a stout, elongate, and coarsely plumose apical 

 seta, in addition to which there is interiorly a smaller sub- 

 terminal seta, also plumose, and three small plain setge 

 exteriorly — that is, on the distal half of the outer margin, as 

 shown in the drawing (fig. 6). Caudal stylets short, narrow, 

 and having a wide space between them; each stylet is pro- 

 vided with a stout, very long, and coarsely plumose apical 

 seta articulated near the base ; there is also a smaller apical 

 seta, the basal part of which forms a stout conical enlarge- 

 ment. 



Halnlat. Lochan a Chaite, on the south-east shoulder of 

 Ben Lawers, Perthshire, altitude 2400 feet above the sea- 

 level ; specimens not very common. 



Remarks. The characters by which the species is distin- 

 guished are the structure of the antennules, the armature of 

 the posterior foot-jaws, and, especially, the structure of the 

 first and fifth pairs of thoracic feet. The short end-joints of 

 the inner branches of the first pair form so marked a character, 

 that by them alone we had no difiiculty in distinguishing 

 specimens of this species from among others of the same 

 genus by the use of an ordinary hand-lens. 



The name we give to this species is the maiden surname of 

 her who, as wife and mother, has, by a lifelong self-denial 

 and ever-ready sympathy, enabled us to overcome difficulties 

 in the course of our natural history studies that would other- 

 wise have been well nigh insurmountable, and whose native 

 home in the beautiful valley of Strathtay is but a few miles 

 from the famous mountain on whose giant shoulder rests the 

 little loch in which the species was found. 



