a General History of the Marine Polyzoa. 157 



turn upwards ; the triplets also speckled, but less strongly and 

 constantly than the stem ; form of the triplets subcordate. 

 Ooecia (?). 



Loc. Jamaica, creeping over an alga [Miss Jelly). 



Amongst the taller stems occur others consisting of a very 

 short and slender internode attached by a corneous joint to 

 the creeping base, and bearing on its summit a single triplet. 

 In these cases growth seems to proceed no further. The 

 primary internode of the ordinary stem is jointed to the creep- 

 ing fibre, and is sometimes normal and sometimes altogether 

 destitute of cells. 



Family Bicellariidse. 



DiACHORIS, Busk. 



Diachoris bilaminata, n. sp. 

 (PI. VIIL figs. 7, 7 a). 



Zoarium (probably) erect, composed of two layers of cells 

 placed back to back ; connecting tubes six, very short. Zooecia 

 large, elongate, boat-shaped, suberect, placed close together 

 and overlapping considerably ; margin running out into a short 

 spinous process on each side of the orifice ; aperture occupying 

 the whole front ; orifice terminal; oral valve arched above, with 

 a straight lower margin ; at a short distance below the top on 

 one side an articulated avicularium (often wanting), slender, 

 rather compressed, the beak long and flat above, bent slightly 

 and abruptly at the extremity; mandible very slender and 

 sharply pointed. Ooecia (?) . 



Loc. New Zealand [Miss Jelly) . 



This diagnosis is founded on a fragment ; and I can there- 

 fore give no account of the size or mode of growth. The 

 zooecia have a strongly marked character, and differ widely 

 from those of any form with which I am acquainted. The 

 layers are closely united, and constitute a very compact bilami- 

 nate zoarium. A striking point is the degree in which the 

 zocecia overlap one another, each cell originating a good way 

 down on the dorsal surface of the one below it. 



The affinity between Diachoris and Beania and Bugula is 

 of the closest kind ; between the present genus and the last 

 named there is indeed but a single point of difference that is 

 at all constant, the disjunct condition of the cells ; and this can 

 hardly be regarded as specially significant*. 



The following species of Diachoris have been described : — 



D. Crotali, Busk, Bass's Straits; D.magellanica, Busk (=Z). 



• I quite agree with Mr. Waters that " the genus Diachoris can only 



be looked upon as a provisional one " (" Bryozoa of Bay of Naples," 



' Annals,' Feb. 1879, p. 120). 



Ann. &Mag. N. Hist. Ser. 5. Vol. vii. 12 



