BRYOZOA OF WOODS HOLE REGION. 263 



Fig. 33. Membranipora arctica, portion of zoarium. 



333. The same, more enlarged, details of cell, ovicell, and avicularia. 



33b. The same, young zooecium at edge of colony, not fully calcified. 

 Fig. 34. Membranipora arctica var. armata, showing large avicularium at base, and small erect spines at 



base of lateral avicularia. 



Fig. 35. Membranipora unicornis, portion of zoarium showing details of various structures. 

 Fig. 36. Membranipora cymbceformis , portion of colony showing general details. 



363. The same, two views of the stalked avicularium, more enlarged. 

 Fig. 37. Membranipora aurita, showing the usual regular arrangement of the cells. 



3;a. The same, more enlarged to show details of ovicell, and the two basal avicularia pointing forward. 



3yb. The same, showing the avicularium pointing backward in absence of ovicell. 



Fig. 38. Membranipora flemingii, enlarged as in 373, with details of cell and ovicell, and the arrange- 

 ment of avicularia in presence and absence of the ovicell. 



Fig. 39. Membranipora tennis, showing partially calcified area with spinules projecting inward, and 

 occasional prominences at angles of zooecia. 



PLATE XXIV. 



Fig. 40. Membranipora tehuclcha, arrangement of zooecia, with details. 

 Fig. 41. Cribrilina punctata, portion of colony with general details. 



413. The same, with curved spines in front of zooecium, enlarged. 



4ib. The same, aperture of young cell with oral spines in usual condition. 

 Fig. 42. Cribrilina annulata, portion of colony with details. 



423. The same, details of cell with oral spines and keel. 



4ab. The same, dwarfed erect cell bearing ovicell. 

 Fig. 43. Porina tubulosa, portion of colony. 



433. The same, more enlarged, details of aperture, ooecium, and pore. 



43b. The same, one of the small frontal punctures highly magnified. 



43C. The same, diagram of side view of cell, ooecium, and pore. 

 Fig. 44. Microporella ciliata, arrangement of zooecia and general details. 



443. The same, a ribbed, umbonate, heavily calcined ovicell, more enlarged. 



44b. The same, elongate form of avicularium, more enlarged. 



44C. The same, a series of forms of the pore showing variations leading from ciliaia to the var. 



stellata, etc., highly magnified. 



Fig. 45. Microporella ciliata var. stellata, the usual heavily calcified condition of this variety. 

 Fig. 46. Hippothoa divaricata, portion of colony. 



46a. The same, ovicell. 

 Fig. 47. Hippothoa hyalina, portion of colony. 



473. The same, at edge of young colony showing spaces between cells. 



47b. The same, dwarfed fertile cell with ovicell. 



47C. The same, details of aperture. 



PLATE XXV. 



Fig. 48. Schizoporella unicornis, portion of colony, the usual form in the Woods Hole region. 

 483. The same, an elongate cell from the same colony as figure 48. 

 48b. The same, smooth, convex form with large umbo. 

 48c. The same, with reversed avicularium, the rcvcrsa of Verrill. 

 48d. The same, ovicell of usual form, and elongate avicularia. 

 486. The same, ovicell heavily calcified, ribbed, and umbonate, from, deeper water, more enlarged. 



