CONTENTS. 



Page 

 No. 1. — Contributions from the Zo<")logical Laboratory. XXIV. Contribu- 

 tions to the Morphology of the Turbellaria. — I. On the Structure of 

 Phagocata gracihs, Leidy. By W. M. \yooDWORTH. (4 Plates.) April, 

 1891 1 



No. 2. — Contributions from the Zoulogical Laboratory. XXV. The Com- 

 pound Eyes in Crustaceans. By G. H. Parker. (10 Plates.) May, 1891 . 45 



No. 3. — Contributions from the Zoological Laboratory. XXVI. On Some 

 Points in the Anatomy and Histology of Sipunculus nudus, L. By H. B. 

 Ward. (.3 Plates.) May, 1891 143 



No. 4. — Three Letters from Alexander Agassiz on the Dredging Opera- 

 tions off the West Coast of Central America to the Galapagos, to the West 

 Coast of Mexico, and in the Gulf of California, carried on by the U. S. Fish 

 Commission Steamer " Albatross." June, 1891 185 



No. 5. — Contributions from the Zoulogical Laboratory. XXVII. The De- 

 velopment of the Pronephros and Segmental Duct in Amphibia. By 

 H. H. Field. (8 Plates.) June [August], 1891 201 



