Vou. 2] Torrey—Hydroids of the San Diego Region. 35 
38. Aglaophenia struthionides (Murray). 
Plumularia struthionides, Murray, 1860, p. 251, pl. 12, fig. 2. 
Aglaophenia franciscana, A. Agassiz, 1865, p. 140. 
Aglaophenia struthionides, Clark, 1876a, p. 262, pl. 41, fig. 3. 
Aglaophenia struthionides, Torrey, 1902, p. 73. 
Trophosome. Stems long, strong, often attaining height of 150 mm., 
occasionally bearing stem-like branches; divided obliquely into short equal 
internodes each bearing a hydrocladium. Hydrotheeae with flaring margin 
armed wih 11 irregular teeth: median tooth long, sharp, recurved; next on 
each side long and directed forward, next bent outward. Mesial nemato- 
phore usually reaches level of aperture. 
Gonosome. Corbulae each formed of 8-13 pairs of leaflets; with 3, 
occasionally 2, hydrothecae at base. 
Distribution. Puget Sound to San Diego. This is the com- 
monest hydroid on the coast, frequently cast up on California 
beaches. Corbulae present, January, June, July. 
Gen. Diplocheilus, Allman, 1883. 
Trophosome. All internodes thecate, each internode with an infra- 
calycine mesial nematophore not in contact with the hydrothcea, and a 
supracalycine median sarcostyle without definite nematophore; each hydro- 
theca wita anterior intrathecal ridge. 
Gonosome. Gonangia unprotected. 
Allman founded this genus on the foilowing characters: a 
duplicature of the walls of the hydrotheeae ‘‘ forming an external 
z) 
ealyeine envelope,’’ a shield-like mesial nematophore not adnate 
to the hydrotheca, and the absence of lateral nematophores. 
Bale (’93) has demonstrated that the hydrothecae of the single 
species (D. mirabilis Allman) for which the genus was created 
do not possess the double walls described by Allman, but are 
constructed after the fashion of the hydrothecae of Kirchenpau- 
eria producta Bale, with anterior intrathecal ridges which, from 
certain viewpoints, suggest a duplicature of the walls. Bale has 
also demonstrated the opening of a median sarcostyle above each 
hydrotheea, flanked by webs of perisare between theca and inter- 
node which form a broad, non-typical nematophore. Allman’s 
definition has been modified to accord with these facts. 
All the trophosomal characters of D. mirabilis which have 
been mentioned are found also in K. producta Bale. The strik- 
ing similarity of the trophosomes of the two species leaves no 
doubt of their generic unity, in spite of the absence of the gono- 
