277 



ordinary zoopcia, from which thev dilTer in form and size. In the majority of 

 species the kenozoa>cia are provided with scattered pores, while in a smaller 

 number of species and as it seems in all the species that may be referred to 

 Hippoihoa Hincks, they are entirely without jiores but possess a median, projec- 

 tiufi; portion. In most species as in Chorizopord Broni/niarli the zoci'cia are separ- 

 ated by a number of small openings, which however are wanting in a series of 

 species, e. g. in //. aniuilaris and H. corniita. 



H. annularis Moll. 

 Lepralia annularis Busk, Catalogue of Marine Folyzoa, Cheilostomata, pag. 85, 



PI. XCV, figs. 1, 2. 

 (fls. XXI, figs. 7a-7f). 



The zooecia are elongated, triangular, trapeziform or rectangular, from the 

 proximal end strongly ascending and leiininaling in a j)orlion, which is strongly 

 arched from side to side as well as distally proximally and almost hunched or 

 expanded. The maximum height of this portion is attained approximately in the 

 distal third of the body. On either side of the ajjerture and bent a iiltle towards 

 it there is a short, stout, wide expansion or acropetal spine, which is rounded at 

 the end and looks like a horn. The anter of the oblong aperture (fig. 7 1)) is 

 provided with two lateral margins, which only converge slightly distally and 

 meet in a curve. Its poster has in the centre a very small, transversely oval 

 sinus bounded on each side by a trapeziform process, which is again separated 

 from a small hinge-tooth by a very small indentation. The well-chitinized oper- 

 culum (fig. 7 e), which has an accessory part corresponding to the sinus, is within 

 each lateral margin provided with a long, almost cucumber-shaped groove, which 

 is surrounded by a chitinized margin and probably serves as attachment for the 

 o|)ercular muscles. The distal wall (lig. 7 d) is angularly bent from side to side, 

 and besides the two large distal pore-chambers, through which each zoo'cium 

 communicates with one or t\^o others, we find in each lateral wall either ',i — 4 

 small pore-chambers or 3 openings, which correspond to as many [)ore-chambers in 

 the neighbouring zoo^cium. 1 — 4 small, superficial pore-chambers (lig. 7 c) are 

 found on most zoa-cia, most often on one side, but sometimes also on the other. 

 They' appear near the suture towards the neigbouring zoa-cium and decrease in 

 size distally. Of these pore-chambers the proximal one is situated near the dis- 

 tal wall. 



The ooecia, which occur in shorter or longer, continuous, curved transverse 

 rows (lig. 1 a), are borne by short, broad, conically cup-shaped gonozoa^cia, which 

 are situated on the frontal surface of the zooecia and communicate with the latter 



