of the Fishery Board for Scotland. 



10:; 



character of the young only, but disappears altogether in the adult."* * 

 Among the Loch Lomond specimens collected near Balmaha there are a 

 few adult females — or, at any rate, females carrying pseudova — which are 

 furnished with a distinct tooth near the top of the head and a little 

 towards the dorsal aspect ; one of the specimens is represented by figure 

 34, Plate VII. t This specimen is, with the exception of the tooth, similar 

 to the more common form without a tooth, of which figure 35 is an 

 example. It is not uncommon to find young Daphnice provided witli a 

 tooth ; but the present specimen is of more interest seeing that it is 

 apparently an adult female. Another female \v\t\i pseudov a has the tooth 

 bidentate (figure 34a). The toothed form appears to be rare iu Loch 

 Lomond, the other with the evenly-rounded head being the more common 

 one. No male Daphnice were observed in this loch. 



The Daphnice of Loch Arklet. (Plate VII., figures 40, 45, 45a.) 



The Loch Arklet Daphnice has been identified by Professor Brady as 

 Daphnia longispina, O. F. Miiller, and as probably belonging to the 

 variety aquiliua, G. 0. Sars. Professor Sars, however, describes his variety 

 as a variety of D. lacustris, and it would almost seem as if that were the 

 more probable relationship. I have already stated that the Loch Lomond 

 Daphnia has been identified as D. lacustris; and if, in connection with 

 that, it is remembered that the overflow water from Loch Arklet falls into 

 Loch Lomond, it is not unreasonable to suppose that the Daphnice of the 

 two lochs should be more or less closely related. There is, no doubt, a 

 certain amount of difference between the typical Loch Arklet female 

 Daphnia and the typical Loch Lomond female ; but it is a difference 

 which might be produced by the difference in the habitat of the two 

 forms. The most obvious difference between the Daphnice of the two 

 lochs is in the contour of the heads of the females. Tn the Loch Arklet 

 female the dorsal curve of the head is not so bold as in that of the female 

 from Loch Lomond, and the head is also proportionally somewhat shorter 

 when compared with the entire length of the body, as shown by the 

 figures (figures 35 and 40). In the specimen figured (figure 40) the 

 number of preanal spines is fourteen, and the post-abdominal processes are 

 small (figure 45). In another and slightly larger specimen the preanal 

 spines number sixteen, and the processes are moderately elongate (figure 

 45a). It may also be remarked that an adult female Daphnia from Loch 

 Lomond carried fourteen preanal spines and possessed long post-abdominal 

 processes — both of which characters are by no means uncommon among 

 the Loch Lomond Daphnice — thus indicating still more clearly the 

 relationship of the Daphnice of the two lochs. 



Th Q Daphnice of Loch Katrine. 



The Daphnice observed in Loch Katrine belong to D. galeata, G. O. 

 Sars. They did not exhibit such a variety of form as those of the same 

 species from some of the other lochs which will be referred to, but 

 resembled generally the form represented by figure 10, Plate VII. No 

 male Daphnia were observed in this loch. 



* "Revision of the British Species of Daphnia" (p. 232). 



f This is probably the form described by Dr. Richard in his Revision des Cladoceres 

 (Ann. d. sc. Nat. Zool., 1896, p. 307, pi. xxiv., fig. 4) as Daphnia lacustris, var. vicina. Dr. 

 Richard's specimens of this variety, which were obtained in Loch Leven Kinross are con- 

 sidered by Dr. Brady to be merely the young of the species named ; whether that be so 

 or not, there can be no doubt that the form referred to here as possessing a vertex tooth 

 is to all intents and purposes "adult " 



