MUSEUM OF COMPARATIVE ZOOLOGY. 163 
SIPHONOPHORA. 
Agalma elegans, FEWKES. 
A. elegans is generally found once or twice each summer in Narragansett 
Bay. It appears with striking regularity about the end of the month of 
August. 
In order to illustrate the general form of the adult there is given a life- 
size figure of one of the largest of these animals which was taken (Plate X.). 
Figures of the more important members of the colony and of younger stages 
can be found with explanations on Plate IX. The youngest Agalma figured 
in the latter plate (Fig. 2) resembles in some respects the genus A thorybia, 
and on that account is called the Athorybia stage. It is characterized by em- 
bryonic covering scales, which have serrated edges, and by peculiar tentacular 
knobs (Figs. 9, 9*). Nectocalyces are not formed in this stage, and the float 
is surrounded by acrown of covering scales fastened to an embryonic stem, which 
is later absorbed. The covering scales of the adult Agalma (Figs. 3, 4) are not 
serrated along their margins, although their edges are crossed by rows of lasso 
cells (Figs. 11, 18), the tips of which, when seen in profile, impart the appear- 
ance of a serration to the border of the scale. The embryonic tentacles of the 
Athorybia larva never develop into those of the adult. These two structures, 
or at least the knobs which they bear, are so different in form in larva and 
adult that there is little doubt that they have different functions (compare 
Figs. 9, 9*, with Figs. 20, 21). 
The embryonie knobs do not resemble the tentacular knobs of the genus 
Athorybia, but are not unlike those of Nanomia cara, A. Ag. They bear 
on their distal ends long stiff hairs (cnidofils) which seem to arise from 
peculiar cells in the substance of the knob. They are non-retractile, and can be 
made to separate from or approach each other. All together generally when 
separated at their tips assume a fanlike shape. "The mass of the knob itself is 
made up of large lasso-cells of two kinds, Of these the majority form a pave- 
ment of cells laid side by side, making a cup-shaped body, which is seen in the 
upper basal part of Fig. 9. The second kind of cells lie between these and 
those terminal cells out of which seem to issue the “ enidofils.” The em- 
bryonic knobs have a darker crimson color than that possessed by the adult 
tentacular pendants. 
The embryonic tentacle of the Athorybia larva arises from an embryonic 
polypite (Plate IX. fig. 14, f). This polypite is formed out of the modified yolk 
sac, and differs from the other polypites, which are formed later by the presence 
on the side towards the attachment of the tentacle, of a network of bright red 
pigment spots. The meshes of this latticework of pigment are clearly differ- 
entiated and well marked. This peculiar pigmentation distinguishes the em- 
bryonie polypite. All the others, which arise as simple buds from the stem, 
are destitute of the latticework of pigment found at the base or on the sides of 
