1 66 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I44 



Perlproct. — Supramarginal, longitudinal, in deep groove extending 

 posteriorly to margin. 



Peristome. — Anterior, depressed, subpentagonal, wider than high. 



Floscelle. — Bourrelets moderately developed, vertical sides; phyl- 

 lodes single pored, not widened, only slight crowding of pores (text 

 fig. 140) ; buccal pores present. 



Tub ere Illation. — Adorally, pores only slightly larger than adap- 

 ically. 



Occurrence. — Upper Cretaceous (Senonian), Royan, St. Paterne, 

 France. 



Location of type specimen. — According to Desor (1858, p. 266) 

 in the Michelin Collection, which according to Lambert and Jeannet 

 (1928) is in the ficole National Superieure des Mines in Paris. 

 I was unable to find the specimen there. 



Remarks. — This species has been attributed by most workers to 

 Agassiz (1840a), but it is a nomen nudum in that reference. 



Synonym of NUCLEOPYGUS 



LychnidiU'S Pomel, 1883. Class meth., p. 55. Type species by monotypy, Nucleo- 

 lifcs scrohiculatus Goldfuss. 



Remarks. — Lychniditts is indistinguishable from Nuclcopygits. 

 Its type species is very similar to the type species of Nucleopygus 

 and certainly congeneric with it. In both species the test is small, 

 elongate, with supramarginal, longitudinal periproct, inconspicuous 

 petals, pentagonal transverse peristome, moderately developed bourre- 

 lets, slightly crowded single-pored phyllodes, and tetrabasal apical 

 system. 



DESCRIPTION OF TYPE SPECIES 



NUCLEOPYGUS SCROBICULATUS (Goldfuss) 



Plate 25, figures 1-4 ; text figure 142 



Nuclcolitcs sci'obicidalus Goldfuss, 1826. Petrefacta Germaniae, p. 138, pi. 43, 

 fig. 3- 



Material. — Sixteen specimens studied in the U. S. National Mu- 

 seum. 



Shape. — Very small, oval, inflated, rounded margin. 



Apical system. — Anterior, tetrabasal (for an excellent description 

 and figures, see Engel and Meijer (1957, p. 91, text figs, i, 2). 



Ambulacra. — Petals slightly developed, short, with slight tendency 

 to close distally; interporiferous zones approximately same width as 



