126 BULLETIN 125, UNITED STATES NATIONAL MUSEUM. 



The oviccll is globular, placed on the distal zooecium, and of the same nature as the 

 frontal. One or two small triangular oblique avicularia are located on each side 

 of the ascopore. 



,, . A . tha = 0.10mm. ' . f is = 0.70-1.00 mm. 



Measurements. — ^Apertura i , . ,. Zooecia i , ^rr. r.nr^ 



^ { ta = 0.16 mm. I 62 = 0.50-0.60 mm. 



Affinities. — This large species is well characterized. It differs from Micropo- 

 rella californica Hincks, 1883, in its smaller tremopores, its avicularia twice as short, 

 its granular frontal, and its larger dimensions. The vestibular arch is as large as 

 in Microporella ciliata Linnaeus, 1759; it differs from it in its micrometric measure- 

 ments, which are twice as large {Lz= 1.00 mm. and not 0.50 mm.). It differs from 

 Microporella gibhera in the regular form of its zooecia and in its small avicularia 

 placed at the level of the ascopore. 



Although we have not found this species at Santa Barbara, Gabb and Horn's 

 type locality, we do not hesitate to compare our specimens with Reptescharella 

 heermanni Gabb and Horn. Their figure resembles Microporella ciliata Linnaeus, 

 1759, as much as it does the present one, but we believe it best to adopt their name 

 instead of suggesting a new one. 



Occurrence. — Pleistocene: Santa Monica (Rustic Canyon) (rare), and Santa 

 Barbara, California (Gabb and Horn). 



Plesiotype.—C&t. No. 68602, U.S.N.M. 



MICROPORELLA GIBBERA, new species. 



Plate 37, fig. 3. 



Description. — The zoarium is unilamellar. The zooecia are distinct, sep- 

 arated by a furrow, very irregular, gibhose; the frontal is convex and perforated 

 by numerous and rather large spines. The apertura is semilunar, transverse; the 

 peristome is thin, a little salient, deprived of spines, resistant to fossilization. The 

 ascopore is very small and placed in the immediate vicinity of the apertura. The 

 ovicell is large, very globular, irregular, of the same nature as the frontal. The 

 two avicularia are very small and placed lower than the ascopore. 



Mea.urements.~K^.nnv. {^l^ ^ f^ mm^ Zooecia!^/ = 0.90-1 .00 mm. 



I Za = 0.14-0. 16 mm. | fe = 0.60 mm. 



Affinities. — The two avicularia are not constant; there is often only a single 

 one, somewhat a little larger. The form of the zooecia defies description. 



This species differs from Microporella heermanni Gabb and Horn, 1862, in which 

 the dimensions are close, in the irregularity of its zooecia and in its small avicularia 

 placed below the ascopore. 



Occurrence.— Pleistocene: Rustic Canyon, Santa Monica, California (very rare). 



Holotype.—Cat. No. 68603, U.S.N.M. 



Subgenus Diporula Hincks, 1879. 



1879. Diporula Hincks, On the classification of the British Polyzoa, Annals and Magazine Natural 

 History, ser. 5, vol. 3, p. 1.56. 



The operculum is semilunar and closes the ovicell. The frontal is a tremocyst. 

 Avicularia are present. The apertura is horseshoe shaped and is slightly con- 

 tracted by two lateral projections. The concavity of the ascopore is denticulated. 



Genotype. — Diporula {Eschara) verrucosa Peach, 1873. 



Range. — Pliocene-Recent. 



