CONTENTS, Vu 
Page 
On a Curious Phenomenon of Prefecundation observed in a Spionide 
Worm, by M. A. Giard; Some new Genera of freshwater 
Sponges, by EH. Potts; A new Form of Freshwater Sponge ; 
Note on the Structure of the Posterior Foot of Toxodon, by EK. 
D. Cope; Contributions to the Study of the Flagellata, by M. 
Jip iCuastlene os cle ctin siaysre apie rynerehs cneicee ot siel va veseapanelt 386—390 
; NUMBER XLVIIL. 
XL 
=~ XL. On some Arctic Foraminifera from Soundings obtained on 
~ the Austro-Hungarian North-Polar Expedition of 1872-1874. By 
Jobonmmye 15} Jeune, oles, Cela LOG) acoocnecannnanoagnoonon 393 
XII. On certain Points in the Morphology of the Blastoidea. By 
P. HerBert CARPENTER, M.A., Assistant Master at Eton College. 418 
XLIT. On the Genera Ctenoptychius, Agassiz; Ctenopetalus, Agas- 
siz; and Harpacodus, Agassiz. By Jamus W. Davis, F.G.S8., F.L.S. 424 
XLII. The Organization of Cenogoniwm, and the Theory of 
Hichens Me by Drop VOGEE Rais siete ccm inal sees arene meee nee 497 
XLIV. Report on a Collection made by Mr. T. Conry in Ascension 
Island. By Dr. A. GintueEr, H. A. Smiru, E. J. Mimrs, C. O. 
WATERHOUSH, Ky Jy snizny andes On oruED Bivens seen ese ... 480 
XLV. Description of a new Species of the Genus Archaster from 
ste Jalellemar,, LBs 18; diioisgeiony Jexooim, MIN, S ooooneadeonscboncoese 440 
XLVI. Description of two new Species of Shells.) By EpeGar A. 
SS MiVASELomey sgt ere cette teats nc i oRctotn ch taderey ian edt av een oh SNL ote eee 44] 
New Book:—The Formation of Vegetable Mould through the 
Action of Worms, with Observations on their Habits. By 
Cieisinsls Deena, Ili ID IIS aooccadsgaaduegon0caceds 443 
Dutch Mollusca, by J. Gwyn Jeffreys, LL.D., F.R.S.; An Abbrevi- 
ated Metamorphosis in Alpheus heterochelis, by A. S. Packard, 
Jun.; Observations on the Rotifera of the Genus Melicerta, by 
M. Joliet; Addendum to our Knowledge of the Carnosa, by H. 
J. Carter, F.R.S. &c.; On the Circulatory System of Spatangus 
purpureus, by M. R. Koehler; Jurassic Birds and their Allies, 
by Prof. O. C. Marsh ; Contributions to the Natural History of 
the Compound Ascidia of the Bay of Naples, by Dr. A. Della 
Valle; On the Vitality of the Germs of Artemia salinaand Ble- 
pharisma lateritia, by M. A. Certes; The Tertiary Lake-basin 
of Florissant, Colorado, by 8. H. Scudder; On the Nature of 
Craropiycus by, CRW Nialcottr cer mera sess 446-—459 
