112 REPORT OF NATIONAL MUSEUM, 1887. 



to Cape Horn, the species of East America, and the general collection 

 of exotic species. In the latter we have two subordinate divisions 

 which are contained in one room with the East American series, but 

 independently arranged. These are (1) the Jeffreys collection of North 

 Atlantic, North European, and British shells, and (2) the collection of 

 Arctic marine shells from all parts of the Polar basin and adjacent 

 waters. Amoug the land shells of North America, a case is devoted 

 to the types of Binney, and in the same way, when received and ar- 

 ranged, the Lea collection of Unionidae and other fresh-water types will 

 form a special series. 



In this connection it is my sad duty to refer to the death, December 

 8, 1886, of Dr. Isaac Lea, for many years the oldest living American 

 student of mollusks, and known all over the world for his researches on 

 the Naiades, especially of North America. Dr. Lea had been a valued 

 correspondent and friend of the Museum from its earliest stages, and 

 had given large numbers of valuable specimens to the collection. In 

 his will, subject to certain reasonable conditions, he left his entire col- 

 lection of Mollusca to the Museum, which, when received and arranged, 

 will pur the Department of Mollusks, in the matter of Naiades, far in 

 advance of any other existing biological museum. 



The administration on our material is progressing so rapidly that it 

 already exceeds our case room. I shall therefore be obliged to make 

 requisition for some eight new cases with their accompanying drawers, 

 etc., to accommodate the general exotic series. 



The few persons available for work on the collection of mollusks, re- 

 cent and fossil, have been engaged with the greatest assiduity in the 

 labor above described, so that comparatively little work has been possi- 

 ble on the large and valuable collection of cephalopods and other mol- 

 lusks in alcohol. They have been examined, however, to determine their 

 safety, and a card catalogue of the collection begun, to be taken up as 

 occasion serves. Though not available for certain sorts of work, the 

 alcoholic specimens afford opportunity for determining with certainty 

 many points of prime importance in classification ; as in one case during 

 the past year in the matter of the gills of Secera (—Cuspidaria) this ma- 

 terial enabled the remarkable fact to be determined that specialized 

 gills of the ordinary form are entirely absent, thus reudering necessary 

 the revision of the definition of the entire class and even the final rejec- 

 tion of one of the most commonly received class appellations. The im- 

 possibility of getting rare exotic material in a living condition will always 

 give to a well-preserved alcoholic collection a certain importance. 



The full list of accessions to this department will be found by refer- 

 ence to Section v of the report, and includes seventy-five numbers. 



Among the more important of these are the series of deep sea mol- 

 lusks dredged by the Coast Survey steamer Blake, types of the report 

 on the mollusks of the Blake expedition by the curator, presented 

 by Prof. Alexander Agassiz ; thirty-two species of Scalaria and allied 



