NOTES ON FRESH AND BRACKISH-WATER ENTOMOSTRACA 23 



to the Cladocera, while the remainder was about equally 

 divided between the two groups mentioned above. 



A small portion of the north shore bordering the Water- 

 side Road had been examined during an earlier visit, viz. on 

 6th July, when about twenty species of Entomostraca were 

 obtained, five of which were not observed in August. On 

 6th July the tide was flowing, and while watching the 

 gradual and steady advance of the water upon the land, I 

 noticed myriads of Schizopods crowding up with the advanc- 

 ing water, all of which appeared to be eagerly seeking for 

 and catching the minute organisms that were being stirred 

 into activity by the incoming tide. A single dip of the 

 hand net was sufficient to capture a considerable number 

 of these busy crustaceans, and when examined at close 

 quarters they were found to consist entirely of Neomysis 

 milgaris (J. V. Thompson). Lower down the river, where 

 the conditions become more estuarine, there are forests of 

 tall reeds growing along the river side ; here in pools in the 

 mud the curious amphipod Corophium grossipes was obtained. 



The total number of Entomostracan species captured 

 during my three visits to the Ythan is sixty-five, seventeen 

 of them belonging to the Cladocera, twenty-six to the 

 Ostracoda, and twenty-two to the Copepoda. Included 

 amongst these were seven species of the Ostracoda and six 

 of Copepoda which are more or less decidedly brackish-water 

 forms. 



The following are the names of the species captured on 

 these three occasions, their abundance or rarity being 

 indicated by the following abbreviations c. = common, 

 n.c. = not very common, r. = rare, and v.r. = very rare ; a 

 blank, that it was not obtained at that particular visit, and an 

 ; is placed opposite the names of the brackish-water species. 



CLADOCERA. 



ist Visit, 2nd Visit, 3rd Vi-,it, 

 July 6. July 13. Aug. 24. 



Ceriodaphnia quadrangula, Miiller . . n.c. 



Scapholeberis mitcronatus, Miiller ... n.c. 



Simocephalus vetulus, Miiller ... c. 



Daphnia longispina, Leydig . . . n.c. 



Bosmina longirostris (Miiller) ... c. 



Ilyocryptns sordid us (Lieven) c. c. c. 



