38 BULLETIN 16 5, UNITED STATES NATIONAL MUSEUM 



almost straight proximal border. The ovicell is hyperstomial, deeply 



embedded in the distal zooecium, closed by the operculum, large, 



globular, smooth. 



Measurements . — 



. fZ.s=0.5 mm. ~ . \ho = 0.12 mm. 



Zooecia, AOKn/1K Opesmm{ msno™™ 



J Iz = 0.35-0.45 mm. \lo = 0.15-0.2 mm. 



25 or 26 zooecia in 4 sq. mm. 



Structure. — As the distal border of the mural rim is not visible 

 under the ovicell, one might believe that the latter is endozooecial, 

 but by dissection its true nature is easily seen. 



The zoarium is very vigorous. It entirely surrounds other Bry- 

 ozoa and hides its true nature. It attaches itself also to young living 

 Serpulae, which are obliged to widen their spires in order to develop. 

 This is a kind of aggressive commensalism, similar to that which 

 Lecointre, 1929, has noted in the gastropods. 



The opesia of the ovicelled zooecia are larger than the others. 



Affinities. — This species differs from Mollia deshayesi Hagenow, 

 1851, from the Maastrichtian of Limbourg in its somewhat more 

 elongated cells and in the absence of the disjunction between the 

 zooecia. 



Occurrence. — Vincentown limesand : Vincentown, N.J. (rare). 



C oty pes. — U.S.N. M. No. 73883. 



MOLLIA PARVICELLA, new species 



Plate 7, Figure 10 



Description. — The zoarium encrusts shell fragments. The zooecia 

 are distinct, separated by a deep furrow, small, somewhat elongated, 

 elliptical; the mural rim is thin, rounded, little salient; the crypto- 

 cyst is large, smooth, shallow, convex. The opesium is terminal, 

 trifoliate, transverse, with a proximal border slightly convex. The 

 ovicell is hyperstomial, salient, convex, transverse, smooth. 



Measurements. — 



. fZs=0.35 mm. _ . [ho = 0.1-0.12 mm. 



Zooecia 7 OK Opesium 



\ls = 0.25-0.3 mm. L |Zo = 0.15 mm. 



37 zooecia in 4 sq. mm. 



Affinities. — We have observed only 2 specimens of this small 

 species, one of which bears some calcified opesia. 



There is a large distal septula and perhaps distal dietellae are 

 present. The species differs from Mollia lacessitor, new species, in 

 its small zooecial dimensions. 



Occurence. — Vincentown limesand : Very rare at Noxontown 

 Millpond and 2 miles southwest of Odessa, Del. 



Holotype— U.S.N.M. No. 73884. 



