ADDITIONS TO BEKWICKSttIRK SNTOMOSTRACA. 259 



for permanent marks of dissimilarity to that species. The specimens which I 

 have described are both males, which are sometimes distinguished by minute 

 differences from the other sex. N'6t uulikely, the beautiful pubescence may 

 perish in long kept specimens. It is by much the prettiest species of the 

 genus. 



Additions to the list of Entomostraca found within the li- 

 mits of the Berwickshire Naturalists' Club — with a De- 

 scription of the Caligus Striimii. By W. Baird, M.D., 

 F.L.S., &c. 



Since the publication of my paper on the " Arrangement 

 of the British Entomostraca with a list of Species, particu- 

 larly noticing those which have as yet been discovered with- 

 in the limits of the Club," Vol. ii. p. 145, I have ascertained 

 the existence of two species which had not then been noticed. 

 1st. Bosmina cornuta, p. 149. — I have now no doubt of 

 the identity of MuUer's Lynceus longirostris with this ani- 

 mal — and therefore, in accordance with the law of priority, 

 I propose naming it the Bosmina longirostis. This exceed- 

 ingly curious little creature I found in the summer of 1846 

 in Yetholm Loch, along with the following. 



2d. Daphnia mucronata, p. 148. — A very good figure and 

 description of this species is given by De Geer under the 

 name of Monoculus bispinosus. The name given to it by 

 MuUer, however, was published in his Zool. Dan. Prodr. pre- 

 viou<5 to De Geer's work making its appearance, and there- 

 fore the name of mucronata must stand. 



The Alona (Lynceus) quadrangularis, p. 151, occurred 

 along with these two species, in the same part of the loch. 



In 1845 I found upon a salmon at Berwick a species of 

 Caligus which, at that time, I thought was new ; marking 

 it, however, with a doubt in the list then published, p. 157. 

 Upon more careful examination I found it approached 

 very near the Caligus Vespa of M. Edwards, differing, 

 however, considerably in size and other more minute dis- 

 tinctions. In the Copenhagen Transactions, VoL 10, p. 23, 

 and t. 7, f 1 — 6, the celebrated Strom has described and 

 figured a species of Caligus under the name of "Laxe 

 luus" o r salmon louse, and which he shortly defines " Mono- 

 culus thoraco abdomineque ovata, cauda lobata.*' It is evi- 



