AKT. 22. CYCLOSTOMATOUS BRYOZOA CANU AND BASSLER. 79 



to the frontal plane; we have not had the opportunity to discover 

 such a specimen and to verify the figure given by Gregory. The 

 latter appears to be rather a tangential section. The orifices of the 

 tubes are oblique, irregular, grouped at the extremity of the pinnules. 

 The exterior decoration of the zoarium is very curious. The ad- 

 ventitious pores are arranged in longitudinal rows and open trans- 

 versally. In the sections this very irregular arrangement does not 

 exist and the adventitious tubes, vacuoles or nematopores are here 

 of a disconcerting irregularity. 



The orientation of the tubes on a single face of the zoarium 

 does not appear in itself a good generic character. It is remarkable, 

 however, that in most cases all the species of the same genus have 

 the tubes equally oriented. 



Occurrence. — Cretaceous (Turonian) : Fontaine d'Antoigne, near 

 Chatellerault (Vienne), Connerre, St. Calais, and Dunneau (Sarthe), 

 and Luynes (Indre-et-Loire), France. Danian of Denmark. 



Cretaceous (Coniacian) : Tours (Indre-et-Loire), France. 



Plesioty pes. —Cann collection and Cat. No. 6899G, U.S.N.M. 



DESMEPOKA RUGOSA D'Orbigny. 1850. 



1S.50. OscuJii)ora ruyosa d'Oebigny, Prodrome de paleontologie stratigrapli- 

 ique, vol. 2, p. 268. 



1909. Semicytis rugosa Gregory, Catalogue Fossil Bryozoa in British Mu- 

 seum, Cretaceous, p. 119, pi. 3, figs. 3, 4 (Bibliography, geologic dis- 

 tribution). 



Historical. — Gregory was the first to perceive that this species was 

 not similar to the other Semicytis described by D'Orbigny ; he recog- 

 nized its exact structure in introducing it in the Desmeporidae. Un- 

 fortunately believing that the other Semicytis were Homoeosolen., ho 

 believed it necessary to preserve the generic name of D'Orbigny for 

 this single species. However, he declared (p. 119) that the two 

 genera Semicytis and Desmeyora are synonymous. In reality Semi- 

 cytis rugosa is indeed a Desmepora^ and we have indicated previ- 

 ously the true nature of the Semicytis of D'Orbigny. 



Stmcture.—ln longitudinal section the tubes are long, little 

 widened, subcylindrical, with irregular dorsal gemmation. Tlie 

 zoarial walls are thick and perforated by short vacuoles. The frontnl 

 nematopores are quite distinct. 



The zoarium is small and much attenuated, so that the preparation 

 of the section is very difficult. The base is a small flat disk. 



Occurrence. — Cretaceous (Coniacian) : Fecamp (Seine inferieure) 

 and Tours (Indre-et-Loire), France, and Chatham, England. 



Pleisiotyjyes.—C^rxw collection and Cat. No. 68997, U.S.N.M. 



