NO. 1-104. PARASITIC CnrEPODS—CALTGW.E— WILSON. 531 



Gcrstaockor published several ^^ears later another attempt at the s3's- 

 teiuatization of this group. His classitication is based almost entirely 

 upon the structure of the appendages and the genital segment, and 

 has remained the accepted classitication up to the present time. For 

 the ]xiper published l)v Bassett-Smith in iSill) can scarcely be called a 

 classitication; it is rather an enumeratiou of species with portions of 

 the synon3'ms. 



In Gerstaeckcr's work there are certain errors which can be cor- 

 rected, and additions which nuist be made in order to bring the group 

 up to date. The latter is especially true of North American genera and 

 species, several of which were omitted by Gerstaecker through lack of 

 identitication. 



The name also, Nogagina, wliich he suggests for his second subfamily, 

 is very unfortunate since the genus called ])y older zoologists Ji^<><j(((ji(s 

 is really made up entirely of the males of other genera. Hence it has 

 no right to )>e continued at all, much less to l)e taken as the tj^pe of a 

 subfamily. Any attempt to preserve this old genus nuist be really the 

 introduction of a classitication based entirely upon males into the midst 

 of another which considers both sexes equally. 



Furthermore it does not seem that (lerstaecker's arrangement shows 

 as clearly as might l)e done the gradual transition from non-degenerate 

 forms like (^allgris and LepeopJithdrio^ through those which show the 

 beginnings of degeneration, like Glolojxjtes and Alehion^ down to 

 Pavdarics and Ceci'ops which are manifestl}^ ([uite degenerate. 



The monograph published by fl. D. Dana in 1852 on the Crustacea 

 of the Wilkes Exploring Expedition contains the oid}" attempt at a 

 classitication of the parasitic copepods thus far made by an American. 

 He divides the group into three tribes according to the structure of 

 the cephalothorax, the presence of a carapace, autl the structure and 

 arrangement of the thoracic legs. He separates the second of these 

 tribes, the Caligoidea, into three families according to the segmenta- 

 tion of the tirst antennje and the structure of the maxillipeds. The 

 second family, the Caligida% he subdivides into four subfamilies on 

 the structure of the mouth parts and the external i^^^ tubes. 



The classitication here presented, like all its predecessors, appro- 

 priates the best in those which have gone before, especiall}' that of 

 Gerstaecker, adds the new genera and species up to date, and such 

 North American forms as have been omitted. It can not claim origi- 

 nality since it diti'ers chietiy in arrangement, but it is hoped that this 

 change in arrangement will show better than heretofore the reUition- 

 ships between the genera. 



