coe: nemerteans of west axd northwest coasts. 81 



forms agree well with those previously made on genera and species 

 in other parts of the world. The region from southern California^ 

 northward, where nearly all the collections on which this report 

 is based Avere obtained, being situated in the temperate and arctic 

 zones, the nemertean fauna would be expected to contain a large 

 proportion of species belonging to the genera Carinella, Emplec- 

 TONEMA, Amphiporus, Tetrastemma, Lineus, Micrura, and 

 Cerebratulus, and these are, in fact, the most abundant genera. 

 Taeniosoma, the genus especially characteristic of the tropics is 

 represented by only three species, of which one occurs only on the 

 tropical coast of Panama and Mexico, and only one species of this 

 genus has been found in Alaska. Drepaxophorus, another genus 

 common in the tropics, is represented by a single species from 

 soiithern California. 



In the arctic region fi-om the Bering Sea northward occur only 4 

 genera and 10 species, so far as these collections indicate. Of these, 

 5 species belong to Amphiporus, so generally common in arctic 

 regions, while 3 species belong to Cerebratulus, another cosmo- 

 politan genus. The remaining two forms belong to Paranemertes 

 and MiORURA respectively. 



Systematic Positiox and Relationships. 



The systematic position of the Nemertini with relation to the 

 other groups of worms is not perfectly clear and is still to some 

 extent a matter of discussion. The best evidence, however, seems 

 to indicate that they should be classed among the platyhelminthes, 

 and that they are more closely related to the Turl^ellaria than to 

 any other existing group, although they have many points of siiui- 

 larity with the annelids. 'I'hey certainly constitute a very highly 

 specialized and aberrant group which, as Biirger ('95, ])p. 709, 711) 

 suggests, may possibly have arisen from an ancestral form of the 

 Turbellaria and then developed along lines somewhat similar to 

 those followed by the annelids. 



In 1851 Max Schultze proposed the division of the group into 

 the two orders Enopla, including those forms in which the proboscis 

 is provided ^Aath stylets, and Anopla, in which stylets are absent. 

 The order Enopla might well be retained, for it includes a well 

 circumscribed group, but the order Anopla has been found to be 



