2 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 9I 



Zooecia bi serial and alternate, very slightly calcified, nearly trans- 

 parent averaging about i mm. in length. The basal portion is nar- 

 rowly tubular for about one-half the length, above which the zooecium 

 expands rather suddenly and extends outward at an angle of about 

 45 degrees. The membranous area occupies practically all of the 

 upper side, extending nearly to the base of the expanded portion, 

 and is turned slightly away from the axis of the stalk. The opercu- 

 lum is semilunar, thickened a little at the border. The distal margin 

 of the zooecium, dorsally, is beset with a row of 4, occasionally 5, 

 exceedingly elongate, tubular, slightly curved spines, which are jointed 

 at the base. The longest spines are more than twice as long as the 

 whole zooecium, reaching a maximum of about 2.50 mm. A smaller 

 spine occurs at one side of the area near its base, and above this there 

 may be another somewhat larger one. There is no indication of a 

 digitiform process, and all of the spines originate separately from 

 the wall of the zooecium. 



Avicularia are of two kinds. One of these is excessively elongate, 

 ranging from 0.95 to 1.90 mm., averaging around 1.40 mm. This 

 form originates on one side near the distal end of the aperture. It 

 has a long tubular stalk, jointed at the base, and expands but little 

 until near the distal end. Both beaks are hooked, the mandible more 

 strongly. There is much variation in the size of the mandibulate 

 portion, the largest being only slightly smaller than the zooecia, the 

 smallest very narrow in comparison. This variation in size is not 

 coordinated with the length of the pedicel. The second type of avicu- 

 larium is very short and small in comparison, being only about 

 0.20 mm. in length. The mandible is noticeably more transverse than 

 in the elongate form. This type is usually attached laterally near the 

 base of the zooecial expansion. They are much less numerous than 

 the elongate type and seem to appear more frequently just above the 

 bifurcation of a branch. There are some infrequent evidences of 

 intergradation in size, but not in position, between the long and short 

 types. 



The ovicells are not abundant, but i or 2 appear on nearly every 

 branch. They are moderately large, about 0.32 mm. in width, some- 

 what globular, the rim of the aperture a little flaring, the surface 

 decorated with radiating lines. They are attached laterally at the 

 distal end of the zooecium, in front of the elongated spines. 



The radical fibers arise from the side of the zooecia near the base 

 of the membranous area, more frequently from the basal zooecia of 

 the branches. They follow the stalk down to its point of attachment 

 where they spread out on the substratum for anchorage. 



