Vlll CONTENTS. 



Page 

 LXVII. Descriptions of some new Species of Birds. By Arthur, 

 Marquis of Tweeddalk, F.R.S o33 



LXVIII. Description of a new Species of Bulimus from South 

 Africa. By Edgar A. Smith, F.Z.S. &c o;J8 



Remarks on the Yellow Ant ; On some Points in the Organization 

 of the Bryozoa, by M. L. Joliet ; On the Coloration of tlio Opti- 

 cal Elements in Locusta viridissima, by M. J. Chatin; On a new 

 Marsupial from Australia, by Prof R. Owen, F.R.S. &c. . .o39 — 542 



Index ' 543 



Arctic Crustacea. 



New Ilvdroids from the White Sea. 



PLATES IN VOL. XX. 



.ATE I. Arctic and Antarctic Sponges. 



II. Carboniferous Polyzoa— Salenia varispina '^ 



111. 



IV. 



VL 



VII. Salenia profundi. 



VIII. Arctic Spiders. 



IX. Siliceous Skeletons of Sponges. 



X. Itellidia Hunlii. 



XI. Ilancockia eudactylota. 



■ \ Pteroplax cornuta. 

 XIII. i ^ 



YIV I 



^vi V . (^ pQggjj Hyalonema and other Sponges. 



XV. ^ ^ 



XVI. Rotalia spiculotesta. 



