914 ADDEKDA TO THE AUSTRALIAX IIYDROMEDUS^, 



The stem is simple, unbranched, and rises from a reticulate 

 Hydrorhiza to a height of 12-18 mm. 



Gonoi)hores oblong, rather lax-ge, on short peduncles. 

 Locality : Lyttleton, New Zealand. 



10. GENUS. DIPHASIC. Agassiz. 



69a (235) DIPHASIA RECTANGULARIS. Nov. Spec. 



Plate XLL, Figs. 6, 7, 8. 



Prom an anastomosing thick Hydrohiza, which is adnato to 

 shells and other hard bodies, thick and rough, straight stems grow 

 forth, which attain a height of 9 Cm. They taper towards theto]). 

 These stems bear alternate Pinnse, which are shorter towards the 

 end, and appear longest near the base, from 2 to 14 mm. in length. 

 Towards the tops, where growth is going on rapidly, the Hydrothecse 

 stand at right angles to the stem. Pinnse, and stem bear the 

 Hydrothecfe which are close to one another, and appear biserial, 

 but otherwise disposed in a very irregular manner. Further down 

 the stem and Pinnae they are disposed in a perfectly regular 

 manner. Here they are distant and alternate. (Fig. 7.) They 

 are tubulai', and bent in the shape of a knee, at a right angle in 

 the middle of their length. The proximal half is immersed in the 

 stem, and nearly parallel to it, whilst the distal half is turned 

 outward, and projects at right angles. TJie Hydrotheca has a 

 circular transverse section throughout. The aperture is simple, 

 smooth, oval, and looks obliquely outward and forward. (Fig. 7.) 



The Qonophors spi'ing from the stem at the bases of same of the 

 Pinnae. (Fig. 6.) The male Polypostyls are invested by a very 

 jjretty Gonangium. (Fig. 8.) It is conic, attached with the small 

 end to a minute peduncle, the sides convex, and the base 

 slightly raised towards the circular aperture in the centre. 

 Eight or more ridges run from the aperture to the peduncle. 

 The surface between them is depi-essed into as many valleys, 

 which are particularly well marked on the sides. Fi'om serrate 

 projections in the ridges transverse lines take their origin, 

 which cross the valleys between the ridges. The ridges on the 

 tlat base of the cone are smooth. 



