ZOOLOGY I]^ 1886. 



By Prof. Theodore Gill. 



Introduction. 



The progress of zoology durinj^ the year 188G has been in tlie same 

 lines as during the ])recediDg- years, and with still greater concurrence. 

 More and more attention is being paid to histology and embryology and 

 perhaps at an undue expense to systematic zoology. Systematic zoology 

 scieutifically treated is simply the co-ordination of all fiicts derived from 

 every branch of biology, anatomy, embryology, histology, and physiol- 

 ogy ; but there appears to be a disposition to relegate it to those who con- 

 sider that its chief aim is to serve for identification of specimens, or to un- 

 duly generalize from a very few embryological facts. Such tendencies 

 are hurtfnl to the welfare of zoology, but uudoubtedl}' the tendencies in 

 those directions will, in due time, be corrected. 



As in the previous reports, the language of the original from which 

 the abstract is com[)iled is generally followed as closely as tlie case 

 will permit. It lias however been found necessary to limit the ab- 

 stract to the illustration of the prominent idea underlying the original 

 memoir, and pass by the proofs and collateral arguments. At the same 

 time, it has been often attempted to bring the new discovery into rela- 

 tion with the previous status of information respecting the group under 

 consid?ration. As to the special discoveries recorded, they have been 

 generally selected (1) on account of the modifications the forms con- 

 sidered may force on the sjstem; or (2) for the reason that they are or 

 have been deemed to be of high taxonomic importance; or (3) because 

 the animals j>er se are of general interest; or, finally (4), because they 

 are of special interest to the American naturalist. Of course, zoologists 

 cultivating limited fields of research will find in omissions cause for 

 censure, and may urge that discoveries of inferior importance have 

 been noticed to the exclusion of those better entitled to it. It is freely 

 admitted that this charge may even be justly made; but the limits 

 assigned to the record have been much exceeded, and the recorder has 

 studied the needs of the many rather than of the few. The summary 

 is intended, not for the advanced scientific student, but for those who 

 entertain a general interest in zoology or some of the better-kiiowu 

 classes. 



