242 ENTOMOSTEAC A FROM THE ARCTIC BED. [Junei9I2, 



Appendix Y. — Report on the Ento:mostraca. 

 By David J. Scouefield, F.Z.S., E.R.M.S. 



I HATE examined the sample of the Arctic Bed from Ponders End 

 submitted to me, and have also received picked-out remains of 

 Ostracoda from the washings made by Messrs. Warren, Kennard, 

 and Davies. 



lly own attention was directed mainly to the discovery of the 

 remains of Cladocera, as I had previously found it possible to 

 identify a number of species of this group in samples of the peaty 

 deposit known as ' moorlog ' dredged up from the Dogger Bank. 

 After a considerable amount of search, I succeeded in finding three 

 specimens representing two species, namely Cliydorus sphcericus and 

 Acroperus liarpce (?). In each case only the shell-valves were 

 obtained, the head-shield and all internal parts having disappeared. 

 One of the two specimens of Ch. sphcericus was in the 'ejDhippial' 

 condition, that is, it had undergone the peculiar modification 

 adapting it to receive the resting-egg. The specific determination 

 of the specimen of Acroperus is not quite certain, owing to its dis- 

 torted condition, but the probability is that it is A. harpce. It is 

 very satisfactory to have found these traces of such delicate animals 

 as Cladocera, especially as the recorded fossils of this group are, 

 I believe, neither very numerous nor always reliable. 



With regard to the Ostracods, the numerous specimens were 

 found to belong to about twelve species, representing six genera. 

 The exact specific determination is doubtful in some cases ; but 

 this is scarcely to be wondered at, when it is remembered that with 

 fossils only single valves are available, and that these difi'er in the 

 same species according to the age and sex and often on the right 

 and left sides also. I wish to express my great indebtedness to 

 Dr. T. Scott, of Aberdeen, for very kindly looking over the material 

 and revisiiig my preliminary determinations. 



The following is the comjDlete list of the Entomostraca so far 

 seen from the Bonder's End Arctic Bed : — 



Cladocera. 1 Herpctocypris strigaia (?). 



r^i J 1 ■ i Ilyociipris hradyi. 



Chydorus sphcericus. rnJLn .nndUn. 



Acroperus harpxB ? 

 Ostracoda. 



Candona Candida. 

 Candona neglecta. 

 Candona acuminata (?). 

 Candona lactea. 



Cyclocypris serena. i Candona rostrata. 



Cypris affinis. ■ Li /nn icy there inopinafa (probably 



Cypris sp. the form described as L. incisa 



lierpetocypris reptans. ' bj Dalil). 



All the species are freshwater forms and, so far as determined, 

 still living in this country. I do not think that any of them are 

 characteristically Arctic in character, though probably all are to be 

 found living under Arctic conditions at the present day. 



I may add that I have also found the tests of a freshwater 

 Rhizopod (Arcella vulgaris .?), some egg-cocoons of aquatic worms 

 (leeches or Turbellarians ?), and some foraminifera that are 

 probably derived from the Tertiary beds. 



