1875.] 9 [Annual Report. 



Number of persons taking books, 109 ; number of books 

 taken out, 835 ; a large increase on previous years. 



REPORTS ON SPECIAL COLLECTIONS. 



MOLLUSCA. 



The work of revising the general collection has been com- 

 menced, and quite largely carried out. The plan is essen- 

 tially this : to retain in the display cases only the more typi- 

 cal forms of each genus and subgenus, and to attempt to 

 illustrate no differences lower than those of generic value. 

 The character of the animal of each family is represented, 

 wherever possible, by a model of one of the typical forms. 

 So far, eleven families, one of Gasteropods, Naticidae, and ten 

 of Lamellibranchs, commencing with the Pholadidse, have 

 been worked over in this manner, and eight models have been 

 made. To more fully explain the plan, I give here an analy- 

 sis of the work done upon the Naticidas. Nine genera and 

 three subgenera are admitted in this family by Dr. P. P. 

 Carpenter, and also by H. & A. Adams, in their " Genera of 

 Recent Mollusca." The genera are Natica, Lunatia, Ne- 

 rita, Ampullina, Naticella, Polinices, Naticina, Cryptostoma, 

 Amaura ; the subgenera, Stigmaulax, Acrybia, Sigaretus. 

 To illustrate the genus Natica we have selected eight 

 species, representing the more marked differences in form 

 and in color which occur within the genus ; but this num- 

 ber might be much reduced. The species chosen are 

 canrena, labrella, lineata, maroccana, millepunctata, stercus- 

 muscarum, spadicea and vitellus. For the subgenus Stig- 

 maulax the species sulcata is used. For the genus Lunatia, 

 monilifera, castanea, metastoma, Raynauldiana and solida> 

 and so on through the remaining genera and subgenera. 

 The genus Amaura and the subgenus Acrybia are not rep- 

 resented in the general collection, but are contained in the 

 New England collection. A note in the catalogue indicates 

 this fact, and states where they may be found. It is in- 



