SYNOPSES OF NORTH-AMERICAN 
INVERTEBRATES. 
XIV. THe Hypromepus@ — Part I. 
CHARLES W. HARGITT. 
INTRODUCTORY. 
Tue following’ synopsis was undertaken more than a year 
ago as a section of the “Synopses of North-American Inver- 
tebrates ”’ now in course of publication. Various interruptions 
have delayed its completion at an earlier date. 
While compiled largely from the author’s notes and observa- 
tions made upon the Hydrozoa of the Atlantic coast during a 
period of more than ten years, the form and method of pres- 
entation are patterned after the systematic works of Hincks, 
Allman, Haeckel, and von Lendenfeld. For many of the 
descriptive notes recourse has been had to L. Agassiz’s Con- 
tributions to the Natural History of the United States and to 
A. Agassiz’s Catalog of the Acalephe of North America, as 
well as to those of the authors just named. 
The synopsis is confessedly incomplete in several of ‘the 
orders, specially upon the Campanularidz and Leptomeduse. 
It is, moreover, limited to a comparatively small range of hydro- 
zoan life of American waters, chiefly of the northeastern 
Atlantic coast. Of that of the Pacific coast our present 
knowledge is still too limited to warrant even a provisional 
synopsis. 
The Hydromedusz comprise one of the three generally 
recognized classes of Ccoelentera, of which the others are the 
Scyphomedusze and Anthozoa. While the first two classes have 
been regarded as much more intimately related phylogenetically 
than has the third, it may be doubted whether after all their 
relation may not be quite remote, at least so much so as to 
warrant separate consideration. Hence slight, if any, reference 
301 
