772 The Siphonophores. [ October, 
remote period as the commencement of the eleventh century; 
that we cannot bring it down to the middle of the seventeenth 
century (the only possible subsequent date on the above supposi- 
tion) must be admitted. 
That the peculiar period embraced in plates xx—xxu1 may be 
located where any two cycles meet is certainly true, so far as the 
years are concerned, but judging by the symbols and extent of 
the period, certain signs which seem to indicate the 3d and Ist 
Ahau, and from the fact that the commencement of no other 
cycle, except that with which the grand cycle begins, coincides 
with the commencement of an Ahau, I am satisfied it marks the 
union of two of the greatest Maya periods.? 
ag corer Oe 
THE SIPHONOPHORES. 
IIl—PHYSOPHORID (ANIMALS CLOSELY RELATED TO AGALMA). 
BY J. WALTER FEWKES. “s 
r the two previous articles? in the NATURALIST, We have 
sketched in outline the anatomy and development of Agalma, 
which is regarded as the typical genus of a family of tubular 
jelly-fishes to which is given the name of Physophoride, in dis- 
tinction from others yet to be mentioned, which are but distantly 
related to the type chosen. Before we go further a consideration 
of the different genera found in this family may be of interest [0 _ 
our readers. aa. . 
All the genera now to be described agree in this particular, 
that they have a float, or air bladder, to support themselves 1 the : 
water in which they live. Stem may fail, the attached nect 
calyces, covering-scales and “tasters” be wanting, but the har Ey 
always remains with the feeding-polyps, tentacles and SeXu@™ 
bells represented in some form or other. To trace the — - 
modifications in structure among the members of the group, i 
to show how now one part, and now another is modihenere: 2 
leading to no new plan of structure, is a most interesting er 
e 631, after 
‘ Errata in the First Article.—In second line from the bottom of pag f the 
the words “17th day of the 2d” add “or 15th,” so as to read “ r7th oe 
2d or 15th month.” In third line from the top of page 636, for “ eran " : 
“covering.” In second line from the top of page 639, for “ cach pore 
“ each two periods.’’ , ‘ 
* NATURALIST, September, 1880, March, 1881. 
