372 BULLETIN 100, UNITED STATES NATIONAL MUSEUM 



Measurements. — 



„ . (Z2 = 0.80mm. ^ . ^ . f Tip = 0.15 mm. (with rimule). 

 Zooecia 7 A . . Penstomice , * . 



I Iz «=0.44 mm. [Ip *=0.12 mm. 



Variations. — Many of the zooecia are deprived of avicularia. The 

 latter are small or large (L = 0.15 mm.). The large avicularia are 

 most frequently on the zooecia bordering the fenestrules. The ovi- 

 cells are of great fragility and are rarely entire on dead specimens. 



The zoarium is yellow ; but it is the ectocyst that gives it this beau- 

 tiful color. However, the calcareous zoarium is also lightly tinted. 



Affinities. — At first appearance this species much resembles Retepora 

 monilifera var. munita MacGillivray, 1883; but differs in the absence 

 of an oral avicularium bordering the pseudorimule. 



Biology. — Our specimens were small fragments and dead. 



Occurrence.— D. 4807. Cape Tsiuka, Sea of Japan; 41° 36' 12" N.; 

 140° 36' 00" E. (common). 



Cotypes .— Cat. No. 8169, U.S.N.M. 



Genus TRIPHYLLOZOON Canu and Bassler, 1917 



TRIPHYLLOZOON BISERIATUM, new species 



Plate 48, figs. 9-12 



Description. — The zoarium is free, reticulated with large fenestrules 

 wider than the branches; the trabeculae bear most often 2 longitudinal 

 rows of zooecia; the dorsal is very convex, slightly granulated pro- 

 vided with short vibices and small elliptical avicularia widely spaced. 

 The zooecia are distinct, separated by a little salient thread, elon- 

 gated, subcylindrical ; the frontal is convex, smooth and some- 

 times bears a small avicularium in the vicinity of the peristome of 

 an adjacent zooecium. The peristome is scarcely salient in its 

 proximal parts; it bears a very salient avicularian mucron in front. 

 The ovicell is large, globular, fragile, ornamented with a trifoliated 

 stigma. 



Measurements. — 



. \Lz = 0.45-0.50 mm. Peristomice = 0.06-0.08 mm. 



Zooecia j ^ = Q 2Q mm Fenestrules = 1 .00-2.00 by 0.50- 



0.60 mm. 



Variations. — The dorsal is frequently smooth; the dorsal avicularia 

 are sometimes long and thin. The avicularian mucro is very fragile. 

 It has no precise form on the dead specimens. The trabeculae are 

 not always biseriated and three rows of zooecia are sometimes present. 



Affinities. — This species resembles very much Retepora tessellata 

 variety pubens Busk, 1884, but differs in the presence of a very salient 

 avicularian mucron. It differs from Retepora mucronata Busk, 1884, 

 in the occurrence of large fenestrules and of two longitudinal rows of 

 zooecia instead of 3 to 5. 



