NORTH AMERICAN EARLY TERTIARY BRYOZOA. 



281 



are the lateral lacunae; the openings developed at the extremities are median 

 lacunae. A lateral lacuna consists then of two parts divided horizontally (E), 

 taking their origin in the lateral walls of two adjacent costules. A median lacuna 

 consists of twp vertical portions formed by the distal extremities of two opposite 

 costules (F). 



Classification. For the reception of species of this family, D'Orbigny in 1852 

 created the two families of Escharellidae (without avicularia) and Eschariporidae 

 (with avicularia). These names prevailed for 30 years. 



In 1880 Hincks showed that Cribrilina Gray, 1848, has priority over Eschari- 

 pora D'Orbigny, 1852, and made this genus the type of the Cribrilinidae. 



In 1886 J. Jullien 1 established ih&t.Membraniporella was not a true member 

 of the Cribrilinidae. Thus regarding the family of Hincks in a different sense, 

 especially since he added to it the Steginoporidae D'Orbigny. he gave it another 

 name the Costulidae. 



The classification adopted by the French author is based chiefly on the form 

 of the aperture and on the development of the oral spines. Most of his genera may 

 be preserved with some modification 

 of diagnosis. 



In 1909 Levinsen established 

 that Hincks' family was not nat- 

 ural, that "certain genera have affini- 

 ties with the Anasca and others with 

 the Ascophora. 



Our studies of the American 

 bryozoa confirm Levinsen's views, 

 but we can not discover the true 



lumen pore 



,. -lumen 



median lacuna 



lateral lacuna 

 FIG. 80. Sketch showing structure of a costule. 

 ter Norman, 1903.) 



(Af- 



affinities of each genus, because it is from the larva alone that these can be dem- 

 onstrated. The attention of the zoologists is called to this, as well as to the great 

 number of other unsolved problems in the science of bryozoology. 



Spines more or less joined together occur in the genus Scmpocellaria and in 

 the family Catenicellidae. but the formation of the costules is the enigma of 

 bryozoology. 



The accompanying figures give a summary of the principal genera known in this 

 so-called family. 



Genus MEMBRANIPORELLA Smitt, 1873. 



1873. Membraniporella SMITT, Floridan Bryozoa, Kougl. Svenska Vetenskaps-Akademiens 



Handlingar, vol. 10, No. 11. p. 10. 



Bibliography (anatomical). 1877. BARROIS, Recherches sur 1' embryologic des Bryozoaires, 

 pi. 8, figs. 27, 29, 32. 1899. WATERS, Bryozoa from Madeira, Journal of the Royal Micro- 

 scopical Society, pi. 3, figs. IS. 19. 1903. 0. NORMAN, Notes on the Natural History of East 

 Finmark, Annals Magazine Natural History, ser. 7. vol. T2, pi. S, fig. 8. 1909. LEVINSEN. 

 Morphological and Systematic Studies on the Cheilostomatous Bryozoa. pi. 9. fig. 9. 



The costules are provided with a large lumen of greater or less size, without 

 pores, and are completely joined or are separated by long slits; usually no lumen 



Costulidae, Bulletin de la SociiHc? Zoologique de France, vol. 11. p. 2. 



