76 BULLETIN : MUSEUM OF COMPARATIVE ZOOLOGY. 



portions of the globe. Of these ten species all except one, Emplec- 

 tonenxa gracile^ which is common in Europe, occur also on the 

 eastern coast of North America. Foui- species occur on both the 

 eastern and western coasts of North America, but have not yet been 

 found elsewhere. These are Carinella pellucida^ Zygonemertes 

 viresce/is, Amphiporus cruentatus, and ZygeupoUa littoralis. A 

 single species, AnqjMporus angtdatiis, is common to the eastern 

 and western coasts of North America and Greenland, but is not 

 found in Europe; while the remaining four species — Ceplialothrix 

 linearis, Tetrastemnia dors((Ie, Linens mridis, Cerebratidtis margi- 

 natus — occur on both coasts of North America, as well as on the 

 northern coast of Europe, in the Mediterranean Sea, and elsewhere. 



The relationship of the Pacific coast nemertean fauna with that of 

 Europe and the Mediterranean is, however, much closer than is indi- 

 cated by the identity of species alone, for a number of genera are 

 represented in both regions by very similar, though specifically 

 distin&t, forms. Nemertopsis and Euborlasia are examples of 

 genera having representatives in Euro])ean waters and on the 

 Pacific coast, but of which no species have as yet been found on the 

 Atlantic coast of North America, or in other parts of the world. 

 Then, too, the close relationship of a number of species from the 

 Pacific coast with corresponding European forms is very striking. 

 Examples of very similar, though specifically distinct, forms are 

 Carinella rnhra with (J. polymorp>ha ; C sexlineata, cajnstrata, 

 albocincta, and cingulata with C superha, annidata, and banyidensis ; 

 (J. pellucida Avith (J. linearis ; Nemertopsis gracilis with K. peronea ; 

 several species of Amphiporus ; Tetrastemma hicolor W' ith T. vermic- 

 vlus ; T. nigrifrons with T. tnelanocephalum ; the herma))hroditic 

 T. caecum with T. kefersteini, while a similarly close resemblance 

 holds for species of Lixeus, Micrura, and Cerebratulus. 



Grifliin ('98) considered that the nemerteans of the Pacific coast 

 showed on the whole a closer afiinity to those of Europe than to 

 those of the Atlantic coast of North America, and my own impres- 

 sion is that this view is well founded even though the nixmber of 

 specifically identical forms is so small. When collecting nemer- 

 teans on the Pacific coast it has been a source of almost constant 

 surprise that the forms collected so closely resembled well-known 

 European species with which they were at first sight thought to 

 be identical, yet when critically stiidied almost invariably revealed 



