208 
PACIFIC SCIENCE, VoL XIX, April 1965 
are important enough to serve as generic char- 
acters or to distinguish Pachycerianthus from 
Cerianthus. These mesenteries, however, are 
the first couple of mesenteries to develop and 
could therefore be expected to be the most 
stable in the grown animal. McMurrich (1910: 
23-24) considered the form of these mesente- 
ries to be characteristic, even at the familial 
level. 
In summary, it should be stated that an in- 
' tensive search must be made for the type speci- 
men of P. benedeni. It is not in the collections 
of the Musee Oceanographique de Monaco, the 
Musee de Bruxelles, the British Museum (Nat- 
ural History), or the Museum National d’His- 
toire Naturelle, Paris, the most likely reposi- 
tories. If it cannot be found, it will be neces- 
sary to declare the species a nomen dubium. 
Since the other twelve species presently in- 
cluded in the genus appear to constitute a 
taxonomic entity, the declaration of the nomen 
dubium would necessitate selection of a new 
type species and generic name for the taxon. 
In the meantime, Pachycerianthus is retained 
in the Cerianthidae and includes the following 
species: P. aestuarii (Torrey and Kleeberger, 
1909); P. benedeni Roule, 1904; P. bicyclus 
(Torelli, 1961) n. comb.; P. dohrni (van Bene- 
den, 1923); P. fmbriatus McMurrich, 1910; 
P. insignis Carlgren, 1951; P. johnsoni (Tor- 
rey and Kleeberger, 1909); P. maua (Carl- 
gren, 1900); P. monostichus McMurrich, 1910; 
P. multiplicatus Carlgren, 1912; P. plicatus 
Carlgren, 1924; P. solitarius (Rapp, 1829); 
and P. torreyi n. sp. 
Pachycerianthus bicyclus is distinguished from 
all other members of the genus by having two 
cycles of marginal tentacles but three or four 
cycles of labial tentacles, and lacking craspe- 
donemes but possessing aboral appendices on 
the second protomesenteries and first order 
metamesenteries. Torelli (1961:24-25) states 
that the specimens from which P. bicyclus was 
described may not have reached full growth, 
so that the species may prove to be an imma- 
ture stage of another. Since P. solitarius from 
the same area differs only in the number of 
cycles of marginal tentacles, these species will 
probably prove to be synonymous. 
Pachycerianthus torreyi n. sp. 
DIAGNOSIS: Siphonoglyph running length of 
actinopharynx. Directive mesenteries extending 
well beyond siphonoglyph. Second protomesen- 
teries between once and twice length of direc- 
tives. Metamesenteries having definite MBmb 
arrangement. Mi definitely longer than any 
other mesentery. M 3 longer than M 2 . m 2 and 
m 3 shorter than mi. B x shorter than P 3 . Mi 
with trineme almost to end of mesentery, cras- 
pedonemes scattered over most of its length, 
very short or no mononeme. 
LOCALITIES: Latigo Cove; and just inside 
breakwater, Los Angeles Harbor (type local- 
ity), California. 
HABITAT: 12—18 meter depth; in mud, or 
mixed gravel and mud, bottom. 
HOLOTYPE and PARATYPES: To be deposited 
in USNM. 
DESCRIPTION (based on 10 adult specimens) : 
Coloration of live animals. Column red- 
brown, darkest just below oral disc and toward 
aboral pore, with narrow buff ring immedi- 
ately around aboral pore. Marginal tentacles 
buff (shading to bright pink towards tips in 
one specimen). Oral tentacles darker, with 
purplish tinge. 
Coloration of animals fixed in picro-formol. \ 
Red pigments of live animals faded, leaving 1 
column light yellow-brown, tentacles yellowish 
buff. 
Length in anaesthetic. 13-31 cm (type 18.5 1 
cm). 
Tentacles. Marginal arrangement 2 ( dt ) 43 1 . 
4231.4231.. . Labial arrangement 2 (dt) 313.4232. 
4312.. . or 3 ( dt) 413.4232.43 12... ( type) . In each 
crown division into third and fourth cycles in- 
distinct in some specimens. Directive labial 
tentacle present. Marginal tentacle number ap- 1 
proximately 90-125 (type approximately 100) . 
Siphonoglyph. Running length of actino- 
pharynx. Attached mesenteries 10 (type) or 
12. Hyposulcus indistinct, less than one-tenth 
length of siphonoglyph. Hemisulcus distinct, 
flat orally, continued down directive mesentery 
as a filament without ciliated tracts. 
