344 PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY. 
The general appearance of this species recalls Clarke’s description 
of II. scutum, but differs from this form in all of the details. All 
stems are divided into joints, which are of dissimilar size, many of 
them without branches or hydrothecae. Clarke notes, however, that 
his species is quite variable, and it is possible that the present form 
is one of these variations. 
Dimensions. Height of tropliosome, 35 mm.; length of 
hydranth, .3 mm. ; width of hydranth, .1 mm. 
Habitat. The. under side of the wharf at Bremerton. 
Campanulariidae. 
It is to this family that the majority of the Puget Sound hydroids 
belong, a family which offers the greatest difficulty in classification. 
Hincks remarks in a footnote to his “key”: “In this group the 
tropliosome offers no generic characters. If the reproductive bod¬ 
ies are absent the student must treat it as a single genus and iden¬ 
tify his zoophyte by reference to the specific description.” Generic 
differences based on the absence of reproductive bodies have led to the 
multiplication of species and synonyms, until the family has become 
badly confused. The structure of the liydrotheca, as Hincks inti¬ 
mates, has played little part in classification. The method of repro¬ 
duction, however, is an unsuitable differential. Campanularia and 
Gonothyraea, for example, form reproductive bodies either as sporo- 
phores or as undeveloped medusae which never become free. Clytea 
and Obelia, on the other hand, produce free-swimming medusae, those 
of the latter belonging to the genus Eucope. The trophosomes of 
Gonothyraea and Obelia agree in having a free branching stem, but 
they do not agree in the gonosome. Campanularia, on the other 
hand, includes both branched and simple species. To the branched 
forms Lamouroux gave the name Laomedia and to the simple forms 
the name Clytea. The classification based on the trophosome 
was given up by Hincks as not representing the natural affinities, 
and he, with Agassiz and others, made the gonosome the chief 
differential. 
Allman (’88) limits the genera very strictly to the characters of 
the gonosome, regarding the presence or absence of a free-swim¬ 
ming medusa of sufficient generic value. He distinguishes Campa¬ 
nularia and Obelia in the following manner:— 
Campanularia: “Trophosome. Hydrotheca pedunculate, cainpan- 
