272 



PROCEEDINGS OF THE NATIONAL MUSEUM 



VOL. 106 



Se-Or-L, secondary orifice length. (Us- 

 ually this is an inside measure- 

 ment, especially if the peristome 

 is of any thickness, but if the 

 peristome is exceedingly thin and 

 elevated and invariable in thick- 

 ness throughout the colony it 

 might be an outside measurement 

 from proximal to distal border.) 



Se-Or-W, secondary orifice width. 



Se-Or-Si-D, secondary orifice including 

 sinus depth. 



Se-Or-Si-W, secondary orifice including 

 sinus, width at top. 



Ly-L, lyrula length or height. 



Ly-W, lyrula width. 



Pe-D, depth of the peristomial cavity 

 (distance between primary and 

 secondary orifices). 



Ov-L, ovicell length. 



Ov-W, ovicell width. 



ZC-H, zooecial cavity height (from back 

 to frontal wall; in zooecia which 

 have very thick walls, inside 

 measurements) . 



ZC-W, zooecial cavity, width, inside 



measurements. 

 FW-T, frontal wall thickness. 

 LW-T, lateral wall thickness. 

 M-L, mandible length. 

 M-W, mandible width. 

 Op-L, operculum length or height. 

 Op-W, operculum width. 



CS-L, compensation sac area length as 

 marked on inner wall of the zooe- 

 cial frontal. 



CS-W, compensation sac area width as 

 marked on inner frontal wall. 



OS-L, oral spine length. 



OS-T, oral spine thickness or diameter. 



PN-L, peristomial notch or sinus, length 

 or height. 



PN-W, peristomial notch or sinus, 

 width at widest part just short of 

 the tip or end. 



AP-D, areolar pore diameter at widest. 



Family Umbonulidae 



Family Umbonulidae was established for Umbonula species by 

 Canu (1904, p. 18) without a formal description (Hastings 1949b, 

 pp. 526-527). Since then its characteristics have been formally stated 

 by Osburn (1952, p. 298) and Bassler (1953, p. G196). Hastings, in 

 comparing the genera Umbonula and Hippopleurifera, suggests that 

 the two are related closely enough to be put into the same 

 family — UmbonuJidae of Canu. At present these are the only two 

 genera in the family. 



Osburn sets down the family characters thus: Frontal "a pleurocyst, 

 with strong costules and large pores; the aperture large, suborbicular 

 or subquadrangiilar, without cardelles or very small ones . . . peristome 

 low or wanting . . , ovicell large and hyperstomial or wanting." 

 Bassler states them as follows: "Like Petraliidae but with prominent 

 umbo on zooecial front below aperture and median avicularium; 

 cardelles and lyrules absent." Under Petraliidae he gives the zooecial 

 frontal as a tremocyst and for Umbonula as a pleurocyst. 



The above family descriptions have to be modified somewhat be- 

 cause some of the Hippopleurifera and Umbonula species do not con- 

 form to the above-stated family characteristics — the former in its 

 frontal and the latter in regard to avicularial position and presence 

 of a simulating median denticle. 



