268 PBOF, ALLMAJf ON NEW GENEBA 



thick, having, just above the base, a diameter of ^^j of an inch, 

 irregularly branched ; hydrothecal ramuli dichotomously divided, 

 forming fan-shaped groups, w^hich are disposed upon the main 

 stem in a closely set spiral, a joint for the most part at the 

 proximal side of each bifurcation. Hydrothecse alternate, flask- 

 shaped, with a short blunt tooth at each side of the orifice, sepa- 

 rated from one another by slight intervals towards the proximal 

 parts of each fan-shaped group of ramuli, but closely approxi- 

 mated towards the distal parts, where the base of each hydrotheca 

 is slightly overlapped by the summit of that below it. 



Gonosome. Gronangia forming two alternating rows on the 

 upperside of the bydrotheca-bearing ramuli, each gonangium 

 springing from a point just below the base of a hydrotheca, ob- 

 conical, crowned with eight short thick spines which surround 

 the broad summit, in the centre of which is the slightly elevated 

 orifice ; margin of orifice with minute teeth, which are directed 

 towards the centre. 



Locality. Japan, Capt. St. John. 



This species is especially remarkable for the great thickness of its 

 stem. The thick chitinous walls of the stem are traversed by very 

 numerous irregular longitudinal canals, which, for the most part, 

 communicate laterally with one another and with the great irre- 

 gular central canal. This central canal, in the specimen exam- 

 ined, was bounded by a wall of chitine much thicker, but lighter- 

 coloured, than that which surrounded the more external canals. 

 The remains of the coenosarc were visible not only in the central, 

 but in some of the external canals ; and it is probable that in a 

 living state they were all pervaded by it. 



Thuiaria coronifera. Plate XVII. figs. 1-3. 



TropTiosome. Main stem attaining a height of more than 4 

 inches, sparingly branched, not fascicled, slightly zigzag, carrying 

 dichotomous hydrothecal ramuli, which are spirally disposed 

 around the stem, extending backwards for some distance from the 

 summit. Hydrothecse flask-shaped, alternate. 

 ' Gonosome. G-onangia [female] borne upon the upperside of 

 the hydrothecal ramuli, springing each from a point just below 

 the base of a hydrotheca, obovate, crowned by about nine hollow 

 bifurcating spines, whose length equals that of the gonangium. 



Locality. Japan, Capt. St. John. 



The specimen examined was plainly a part of a female colony. 



