214 BULLETIN OF THE 
As the only figures which we have of Nanomia are of the young, my first 
care was to obtain a figure (Plate I.) of the adult animal. 
The method by which a drawing of the outline of this large Nanomia was 
made may have an interest to those engaged in the study of the Siphono- 
phores. The outlines of Plate I. were drawn in the following way. 
The animal was placed in an upright glass jar, with flat sides, similar to 
those of glass vessels used for the bath in photography. This glass receptacle 
was placed in the bright sunlight, on a table between the observer and the 
window, or some source of light. It was so placed that a well-defined shadow 
of it was projected on the paper held a few inches back of the animal, on the 
side of the glass opposite the window. The paper was tacked to a board held 
upright and firm by simple means, which any one can devise. The shadow of 
the Nanomia was so clearly defined that even the faintest lines of outline were 
seen projected on the paper. There are times when a Siphonophore floating 
in the water keeps almost perfectly quiet for some minutes. This is a good 
opportunity to trace on the paper the lines of the shadow with a pencil. 
Although I could not make the whole contour before a new movement of the 
medusa, it was easy to draw the nectocalyces and sections of the polyp-stem 
before the animal changed its attitude. 
The only trustworthy account which we have of Nanomia is the original 
description by A. Agassiz.* This observer not only described the first long- 
stemmed Physophore from American waters, but he also gave the first series 
of recorded observations on the development of the young of any genus of 
Siphonophores. 
From my own studies of Nanomia I am convinced that the adult of Nano- 
mia has never been figured or described. The reasons for this belief will, I 
hope, appear as I go on in my account. The description by A. Agassiz was 
pioneer work in a field where later observations have been extensively made ; 
yet for over fifteen years Nanomia was the only long-stemmed Physophore 
known from the waters of the United States. His description has been 
repeatedly copied, and his figure is widely used in general accounts of these 
animals. It is found necessary to differ from one or two statements made in 
the original description in regard to Nanomia. These differences are specially 
noted, and a redescription is not made of those points of anatomy where in the 
main my account agrees with that already published. The fact that Nanomia 
more than any other Siphonophore is used in text-books and general descrip- 
tions of marine animals published in America to illustrate the general charac- 
ter of the group, would seem an inducement to publish any contributions 
which might be made in regard to its embryology and anatomy. 
It may be well, at the very threshold of my description, to mention the 
* The best account of the anatomy and embryology of Nanomia is in “ North 
American Acalephe.’’ There are other notices of the same animal by the same 
author, one of the best known of which is in “ Seaside Studies,”’ by Mrs. E. C. and 
A. Agassiz. 
