38 University of California Publications. [ ZooLoGy 
Nutting adds the fact in his description that the hydrocladia 
‘alternate as a rule, but not regularly so in some specimens, 
where they are occasionally opposite toward the distal end of the 
stem. 
The San Diego material consists of two stems, the longest 
measuring 100 mm., both unbranched. The stem internodes vary 
in leneth, due to the obliteration of one or two nodes, and bear 
one, two or three hydrocaldia respectively. The number of their 
lateral nematophores varies with their length, from two to four. 
There is a pair of nematophores on each basal process, also an 
unpaired conical open process from which coenosare projected 
in one ease, and is probably to be reckoned as a nematophore. 
The hydrocladia are slender. In the first formed regions of the 
colony they alternate; in the younger, distal regions they are 
usually opposite, as Nutting has said. A further variation in the 
distal region consists in an alternation of successive pairs of 
hydrocladia, so that the members of every other pair lie in a 
plane making an angle somewhat less than 90° with the original 
plane of the colony. The basal internode of each hydrocladium 
is short toward the base of the stem, with a single mesial nemato- 
phore. In the younger distal part of the colony it is usually 
wanting. Oceasionally a non-thecate internode fuses with a 
theeate internode. The theeate internodes frequently bear two 
mesial nematophores. 
One stem had produced a heteromorphic shoot with several 
hydrocladia alternately placed, as is the rule with the basal part 
of the stem. 
This species appears to be closely allied with P. filicula All- 
man, but its hydrothecae are not so deep and its habit is less 
regular. 
42. Plumularia plumularioides (Clark). 
Halecium(?) plumularioides, Clark, 1876, p, 217, pl. 10, figs. 
NGA 
Plumularia plumularioides, Nutting, 1901, p. 62, pl. 4, fig. 3. 
Plumularia plumularoides, Torrey, 1902, p. 78, pl. 11, figs. 103, 
104. 
Trophosome. ‘‘Hydrocaulus erect, simple, straight, divided by 
transverse joints into internodes of considerable length, regularly branched 
and with a few annulations at the base; branches arranged alternately on 
