66 
THE VOYAGE OF H.M.S. CHALLENGER. 
Thuiaria quadridens, n. sp. (PI. XXXI. figs. 2, 2a). 
Trophosome. — Stem monosiphonic, pinnately branched, joints at irregular intervals. 
Hydrothecse alternate, deep, subcylindrical, adnate to the internode for somewhat more 
than half their height, and then diverging at a rather high angle ; margin divided into 
four teeth, two of which are narrow and situated at the epicauline side, and two broader 
.at the apocauline. 
Gonosome not present. 
Locality. — Station 314, between Cape Virgins and the Falkland Islands; lat'. 51° 35' 
S., long. 65° 39' W.; depth, 70 fathoms. 
Thuiaria quadridens was dredged from the same ground with Sertularia implexa. 
It is a rather slender form of much elegance, and attains a height of nearly two inches. 
Thuiaria pharmacopola, n. sp. (PI. XXXI. figs. 1 , la, lb, 1 c. Id). 
Trophosome . — Stem strongly fascicled below, becoming monosiphonic distally, 
sparingly branched, set with alternately disposed pinnae. Hydrothecse opposite, adnate 
to the hydrocaulus for nearly their entire height, cylindrical, deep, terminating in an 
oblique orifice whose apocauline margin forms an acute tooth. 
Gonosome. — Gonangia borne upon the front of the pinnae, each springing from a 
point in the interval between two pairs of hydrothecse, urniform, with the roof raised as 
a conical projection which carries the circular even orifice on its apex, and is surrounded 
by about six compressed spines. s , 
Locality. — Station 75, off the Azores; lat. 38° 38' 0" N., long. 28° 28' 30" W.; 
depth, 450 fathoms. 
Thuiaria pharmacopola is a large and beautiful species. It grows to a height of 
upwards of si-x inches, while the pinnae, which are rather closely set, may attain a length 
of more than one inch. The stem towards its base is thick and densely fascicled, but 
becomes monosiphonic towards its summit. The hydrothecse composing each pair in the 
pinnae are approximate, but not connate. The intervals which separate the pairs from 
one another are short, and joints occur here and there in the pinnae, but at long and very 
uncertain intervals. 
A transverse section of the stem near its base (fig. lc) presents an areolar structure 
resulting from its fascicled composition, the component tubes being very thick-walled and 
inseparably adnate to One another. Such a section affords a good illustration of the 
difference between the more common forms of fasciculation and the true perisiphonic 
fasciculation of the Perisiphonidse. 
