584 MAYNARD M. METCALF, 



sion Station at Wood's Holl, found a number of Ascidians which have 

 proved of considerable interest, and which, I believe, have helped 

 me to clear up a confusion that has existed as to several American 

 forms. In 1843 De Kay found in New York Harbor an Ascidian 

 which he named Ascidia manhattensis. Verrill redescribed this 

 form in 1871 naming it Molgula manhattensis, by which name it is 

 still known to American students. It is probably the best known 

 of our American Ascidians. It is clearly a Molgula and is apparently 

 nearly related to M. impura of northwestern Europe. 



Tellkampf in 1872 rediscribes the species (probably he had 

 not seen Verrill's paper) and criticises De Kay's description in a 

 number of points especially stating that "the branchial sac is not 

 plicated". In every respect except the non-plication of the branchial 

 sac Tellkampf's description would apply to Molgula manhattensis. 

 Of the habitat of his form Tellkampf says : "I have found it on the 

 north, south, and east shores of Manhattan Island particularly in 

 places protected against the current of the water, attached to brams, 

 boards, or rocks in Sandy Hook Bay, and in the Navesink River to 

 about five feet below the surface of the water." As no other Asci- 

 dian of at all this character is now known to occur in such situations 

 either in New York Harbor or on the New England or New Jersey 

 coast, one can not doubt that Tellkampf was studying the same 

 species De Kay had first described. If this is true then Tellkampf 

 was mistaken as to the alleged non-plication of the branchial sac, 

 for the branchial sac of Molgula manhattensis (De Kya's and Ver- 

 rill's form) is plicated. 



Traustedt 1) describes a form "from the eastern coast of North- 

 America, Cap Cod", which is very distinct from Molgula manhattensis 

 and whose branchial sac is non-plicated. This he names Bostricho- 

 hranchus manhattensis (De Kay). It clearly is not De Kay's form 

 which Verrill has redescribed as Molgula manhattensis. It is a 

 new form whose species name as well as genus name should be 

 ascribed to Traustedt and not to De Kay. 



Herdmania dostrichohranchus. More careful study has shown that they 

 are probably to be regarded as belonging to a new species of the 

 genus Bostrichobranchus and I have therefore rewritten this section. It 

 is however to late to change the references to this species in the earlier 

 pages of this paper and use the proper name. I hope this discrepancy 

 will not lead to confusion. 

 1) Traustedt, 1882. 



