PUGET SOUND NEMERTEANS. 199 



position of the muscular coats of the body-wall in relation to 

 the nerve cords commences for the first time to be recognized. 



But excellent and serviceable as the Hubrechtian system was, 

 it still possessed a defect which became more conspicuous w^ith 

 increase of our knowledge of the comparative anatomy and 

 embryology. It still associated under the term PalVeonemer- 

 TiNi such forms as Carinella, Ccphalotlirix and Polia ( = Eiipolia 

 Hubrecht "^J^, the last named type being more closely related 

 to the ScHizoNEMERTiNi than to Carinella. The following 

 sentence from Oudemans ('85) shows how^ quickly this defect 

 became obvious with careful comparative study. *' Though the 

 families of the Valcnciniidce and the Poliidce belong to the PaL/E- 

 ONEMERTEA, they, with respect to their vascular and nephridial 

 system, already approach the Schizonemertea. To avoid con- 

 fusion, I will here employ the expression, " Pa4^o-type," 

 '' Schizo-type" and " Hoplo-type." Burger ('90) went even 

 further, and, after a severe criticism of Hubrecht's system, pro- 

 posed a return to the Anopla and Enopla of Max Schultze. 

 During the next two years, however. Burger ('91 and '92) elab- 

 orated and published a new system, which of all those heretofore 

 proposed seems to come the nearest to expressing the true in- 

 terrelationship of the main groups of Nemerteans. 



Before taking up Burger's system in detail we must glance 

 briefly at the phylogenetic theories as influenced by the discov- 

 ery of Carinoma. All are agreed that the epithelial position of 

 the nerves in Carinella is a primitive feature. Accordingly the 

 derivation of the remaining Nemertean orders from Carinella-\\kQ 

 ancestors involves an inward migration of the nerve-cords. Even 

 before the discovery of Carinoma a fairly complete series could 

 be arranged from Carinella with its epithelial nervous system, 

 through Cephalothrix with nerve-cords in the longitudinal layer^ 

 to Cerebratulus in which the nerve-cords have apparently migrated 

 further inward to lie closely appressed (and sometimes indenting) 

 the inner circular muscle layer, leading finally to the Enoplous 

 types with the nerves internal to all the muscular coats. (Com- 

 pare figures in Hubrecht "^J ^ 



In 1875 Mcintosh obtained at Southport, England, a spe- 



