Plate 20 



Murronella crozetensis (Waters) 



Figure A: Three zooecia. The peripheral frontal pores, one or two rows, have been 

 enlarged a bit to show them better. Usually they are mere slits, like tiny pin-pricks. Scale c, 



Figure B: A hTula of three points and a flat plane where the straight line is. Thickened' 

 centrally and longitudinal!}'. Scale e. 



Figure C: Peristomial fragment, with bases of two hollow h\"aline spines. Scale e. 



Figure D: A calcareous zooecium seen from underneath. The hca\'y black dots above 

 orifice are spine bases. The heavily stippled radiating canals, yellow or brownish and! 

 membranous in actual specimens, connect the mosth' torn off membranous base of this 

 zooecium with neighboring zooecia. Scale d. 



Figure E: An o\-icelled zoid with 8 peristomial spines. Oviccll slants back from the 

 peristome. Zooecial peripheral pores shown at sides. Scale b. 



Figure F: Another ovicell, uncalcined and tipped forward to show the very long and 

 pointed suboral mucro that characterizes young zooecia. The lateral peristomial rim wasi 

 too obscured and vague to show if and how many peristomial spines were present, so the rim 

 was left unadorned. Other zooecia of the same colony had spines. Scale a. 



Figure G: Another ovicelled zoid showing texture of the frontal, peripheral pores, and 

 the proportion and position of the ovicell with respect to rest of zoid. Scale c. 



Figure H: Side view of 3 uncalcined zoids and the membranous (cross-hatched) base of i 

 fourth surrounded by a calcareous rim. The membranous canals or interzooecial connec 

 tions shown in figures D and K pass through this calcareous border to neighboring zoids! 

 Scale/. 



Figure I: Peristome, secondary oriiice, 7 oral spine bases, and a split 5-point lyrula, seer 

 from the outside. Scale a. 



Figure J: Primary and secondary orifices, 8 oral spine bases, and a 4-point lyrula, seer 

 from the inside. Scale a. 



Figure K: Enlargement of the membranous base canals, such as shown in figure Dl 

 where the corners of 3 zooecia meet. The 2 lateral zooecia show the canals constricted 

 the zooecial distal halves. Canals of the proximal corner (upper middle zoid) are not con-i 

 stricted. Scale g. 



Note: Figures F and H are from natural unrcmo\'ed specimens; the others are frorr 

 calcined and slide-mounted material. Figure F is of material from Station 44, figures T 

 and G from rock at Station 184; all others from "Rock 7," station unknown. Each scnli 

 represents 0.2 mm. 



