ANTARCTIC BRYOZOA — ROGICK 283 



Measurements: Minimum to maximum and average measure- 

 Inents, in millimeters, are given below (for explanation see page 271). 



::-L 0.851-1.184 (1.019) Av-L 0.144-0.187 (0.160, oral avic.) 



:-W 0.481-0.888 (0.683) Av-W 0.086-0.101 (0.094, oral avic.) 



'r-Or-L 0.173-0.216 (0.189) M-L 0.094-0.173 (0.112, oral avic.) 



'r-Or-W 0.209-0.230 (0.218) M-W 0.065-0.094 (0.077, oral avic.) 



.y-L 0.014-0.029 (0.027) Av-L 0.115-0.158 (0.139, frontal avic.) 



.y-W 0.086-0.115 (0.100) Av-W 0.058-0.101 (0.078, frontal avic.) 



,)p-L 0.158-0.187 (0.173) M-L 0.05S-0.066 (0.059, frontal avic.) 



,)p-W 0.228-0.266 (0.251) M-W 0.050-0.072 (0.063, frontal avic.) 



\(^Ot-L 0.158-0.230 (0.194) Ov-L 0.296-0.407 (0.353) 



!^Or-W(anter) 0.180-0.238(0.198) Ov-W 0.370-0.481 (0.429) 

 5e-0r-W (poster) 0.230-0.302 (0.275) 



Zoarium: Some zoarial fragments encrust other Bryozoa and rocks 

 vhile other fragments (edges of colonies) form free, flat, thin, foli- 

 iceous, unilaminate chips. They are ivory-colored, often well cal- 

 cified. Some contain polypides and ovicells with pale orange-colored 

 imbryos. Colonies in the collection are not complete; the biggest 

 Jragment, from Station 190, measures 18 mm. by 24 mm. 



Zooecia: Zooecial shapes vary considerably. Zooecia are usually 

 lexagonal, with the distal half of the zooecium generally broader and 

 ;ounder than the proximal half, and with the distal walls curved from 

 m arch to a modified inverted V (pi. 22,B,C,N). Sometimes even a 

 ^ap occurs in the distal wall (pi. 22, N). The curved-to-angular 

 lateral walls have five to seven pore plates. Zooecial frontal bound- 

 aries are distinct because of the single row of rounded, numerous, 

 dosely set areolar pores which are placed so close to the mural rim 

 jand because of the sudden convexity of the zooecia. The areolar pores 

 are more or less tubular in appearance, the lateral wall of the tube 

 short, the mesiad wall longer, because of the sudden rise of the frontal 

 zooecial wall. The rest of the frontal is nonporous except for two, 

 occasionally three, pores transversely or obliquely placed below and to 

 one side of the oral mucro (pi. 22,A-C,0). These two pores are 

 always present at the base of the oral avicularial chamber but not 

 elsewhere and not in connection with the frontal avicularia. 

 I The olocyst is thin, smooth, areolated. The pleurocyst, also areo- 

 lated, is thicker, and granular to beaded. The ribs between the 

 areolae are prominent but short, and not continuing up very far along 

 the side of the zoid. 



Avicularia: Two types of avicularia, the oral and the frontal, may 

 occur. The oral is present on every completed zooecium (pi. 22, D, 

 E). One or two frontals may occur on some zoids (pi. 22, A-C), or 

 enth'ely absent on others (pi. 22,D,0). The oral avicularium varies 

 from considerably larger down to frontal avicularium size. The 

 avicularial chamber is large in the oral type (pi. 22,L) and small in the 



