242 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 105 



other corners. The visible frontal surface of the zooecia measures 

 0.662 to 0.806 mm. (average 0.752 mm.) in length and 0.518 to 

 0.576 mm. (average 0.552 mm.) in width. The zooecial surface 

 is quite flat except for the salient zooecial orifice and the very 

 thin, slightly raised, low side walls. The two most depressed areas 

 of the zoids are the ovicell and the space just below the lower lip. 

 The cryptocyst covering the front of the zoid is tubercled but the 

 tubercles, though numerous and quite close together, are small so 

 that the front still appears flat, though of a pebbled texture. Many 

 zooecia do not seem to have cryptocyst ridges but some do show 

 faintly raised parentheses-like ridges which begin at the sides of the 

 orifice, near the ovicell walls. The zooecial walls are quite opaque 

 and the hidden underlying parts of the zooecia could not be made 

 out accurately. 



Zooecial orifice: The angular orifice is slightly salient. It is 

 from 0.086 to 0.115 mm. (average 0.105 mm.) long and from 0.173 to 

 0.187 mm. (average 0.183 mm.) wide, and is placed about three-tenths 

 of the zooecial length from the distal edge of the zoid, leaving a wide 

 strip of cryptocyst between it and the distal wall arch. The external, 

 distal border of the orifice is straight, as are the two lateral walls 

 which diverge somewhat proximally. The lower lip is curved to give, 

 the orifice a concave outline. Two conspicuous conical condyles are 

 located at the proximal corners. Two smaller condyles or processes'! 

 are beneath the distal lip. These distal processes are not teeth but 

 are prolonged corners of a calcareous plate or ledge which hangs down 

 into the orifice. The lower border of this plate is concave, the two 

 corners prolonged to form the so-called teeth. The operculum fits 

 the orifice snugly. It is angular, yellow, and chitinous, with distal 

 edge straight, distal corners gently curved, and lateral sides diverging 

 slightly proximally. Its proximal border is concave and its rim is 

 reinforced with chitin. 



OviCELLs: These are located largely between the distal lip of the 

 zooecial orifice and the distal zooecial arch. They are basinlike. 

 Whether they are merely incomplete, not yet bridged over by a 

 calcareous front, or are fully formed and covered only by a membra- 

 nous frontal wall is not certain. One zoid on a single cyclostome- 

 supporting branch appears to suggest the latter alternative. The 

 ovicell surface is depressed and faintly, closely tuberculate (pi. 7,E) 

 like the rest of the zooecial frontal. Its side walls are faintly raised 

 and shaped like parentheses. The cavity of the ovicell measures 

 0.187 to 0.216 mm. (average 0.200 mm.) in length and 0.209 to 

 0.245 mm. (average 0.225 mm.) in width. 



Avicularia: The avicularia (pi. 7,C,II) are small and vicarious 

 and resemble in some respects those of Melicerita latilaminata (pis. 



