86 PROCEEDINGS OF THE NATIONAL. MUSEUM vol.67 



We have sectioned a specimen containing on one side an exterior 

 accessory intrazoarial lamella. It is a curious phenomenon which 

 we have observed for the first time. 



On the broad sides the peristomes are arranged irregularly on the 

 median axis and in laterally transverse lines, an arrangement close 

 to that observed in Hornera. 



Occurrence. — Lower Cretaceous (Aptian) : Grandpre (Ardennes), 

 France; Faringdon, England (common). 



Plesiotypes.— Cat. No. 69941, U.S.N.M. 



LATEROCAVEA INTERMEDIA, new species 



Plate 13, figs. 9-17 



Description. — The zoarium is small, cylindrical, dichotomously 

 branched. On the principal branches the orifices are arranged lat- 

 erally, although the entire anterior surface is occupied by mesopores. 

 On the terminal branches the orifices are disposed entirely around 

 the colony. In the cellular parts the orifices are arranged in irregu- 

 lar transverse lines; the peristomes are almost always adjacent and 

 separated longitudinally by groups of four mesopores. The ovi- 

 cell is globular, elliptical, large, and always placed on a side with 

 mesopores. 



Measurements.— Di^tmeteT of orifice, O.OS mm.; zooecial width, 

 0.14 mm.; distance of orifices, 0.25 mm.; diameter of branches, 

 1 mm. 



Affinities. — The arrangement of the orifices is absolutely contrary 

 to that in Laterocavea dutempleana D'Orbigny, 1S53, because they 

 arc lateral and not on the plane of dichotomisation. Furthermore, 

 the small branches, bearing orifices entirely around the colony, offer 

 the aspect of Petalopora Lonsdale, 1850. Complete zoaria present, 

 therefore, all the characters intermediate, between the two genera 

 Laterocavea and Petalopora. This species differs again from Latero- 

 cavea dutempleana D'Orbigny, 1853, in its rounded instead of com- 

 pressed and much smaller branches. 



Occurrence. — Lower Cretaceous (Aptian): Faringdon, England. 



Cotypes.—C&t. No. 69942, U.S.N.M. 



Genus SIPHODICTYUM Lonsdale, 1849 



1849. Siphodidyum Lonsdale, Notes on Fossil Zoophytes, Quarterly Journal 

 Geological Society London, vol. 5. p. 94. 



The ovicell is an elliptical, very convex sack, perforated by a 

 certain number of tubes (type of Ascosoecia) . The tubes are short, 

 with peristome, with triparietal gemmation around a central axis. 

 The zoarial epitheca is very thick and perforated all around the col- 

 ony by small numerous vacuoles, issuing from aborted tubes and 

 arranged at the bottom of the sulci. 



