THE MORPHOLOGY OF THE CHKILOSTOMATA. 349 



correspond witli the vitta of t,lie next species. The frontal shield (/. s/;.) is 

 Cribrilina-like. — Victoria (Challenger Collection). 



Fig. 50. — Vittaticella cornuta, Busk. — Distal end of an old zooeciiiiu 

 with a young " bii:lobulus ; " j , fully formed cliitinnus joint ; 7.', yonng joints 

 //., the lateral horns ; h.', vestifjial horn of the proximal zooeciuni of the liiglo- 

 bulus; v., vittae, filled with deeply stained material in the young zorecia. The 

 compensation-sac (e. s.) is fully developed in the proximal zonecium of the 

 biglobuius, and is quite young in the distal zooeciuni. — Victoria. 



Fig. 57. — Micropora, sp. Basal view, showing the lateral recess (A ;•.) 

 of the cryptocyst, containing the depressor muscle (depr.), and giving ofl' 

 distally a calcareous (lange, from which the oocliisor muscle (ore/.) originates. 

 — Torres Straits. 



Fig. 58. — Micropora, sp. (from the same slide). Frontal view, showing 

 the cryptocyst {cri/pl.) with the two lateral recesses (/. r.), and the depressor 

 muscles (depr.). 



Fig. 59. — Ichthyaria oculata. Busk. Zonecium preceding a i)ifurcation 

 of the branch, and therefore less curved than most of the zooecia. The com- 

 pensation-sac (ex.) opens by the "median" pore (w../5.), which is asym- 

 metrical; s.s.', sutures in calcareous wall. — S.E. of Buenos Aires (Challenger 

 Collection, Stat. 320). 



Fig. go. — Calwellia sinclairii, Busk. — Seen somewhat, nl)liquely. The 

 compensation-sac (^. 5.) opens l)y the crescentic median pore (m.p.). — S. of 

 Kerguelen Is. (Challenger Collection, Stat. 158). 



Fig. 61. — C. gracilis, Maplestone. Young zooecium and parts of its 

 neighbours. — Victoria. 



Fig. 62. — C. gracilis (from the same slide). Two mature zoeecia, showing 

 the large compensation-sacs (c. s.); c. p., comnuinicat ion pores ; prox., the 

 narrow proximal part of a distal zooecium. 



Fig. G3. — Microporella malusii, And. Basal view of a zooeciuni which 

 has lost its polypide ; d., polypide bud ; r. s., conipensal ion-sac, opening by the 

 median pore (m.p.); corn., JuUien's " cornicula ; " p.c, porc-chambrrs ; z. 

 neighbouring zooecia. — Naples. 



Figs. 61 — 66. — Steganojiorella alveolata, Harmer. — Torres Straits. 

 Fig. 61. — B-o])erculum with its occlusor muscles, seen from the inner 

 side, and somewhat distally, so as to be considerably foreshortened; cond., 

 condyles, united to the basal sclerite (b. s.) of the operculum by the strong 

 ligaments, lie/.; occL, proximal occlusor muscle, the tendon (letid.) of 

 which is inserted into the occlusor tubercle (occl. L) of the operculum, 

 and gives off a fascia (f.) which connects it with llie projecting pnixinial 

 end of the main sclerite (/«.«.) ; occl.', distal occlusor, inserted into the 

 fascia /.' ; .r, line along which the operculum passes into the roof of the 

 vestibule (cf. Fig. 26). 



