ART. 14 FOSSIL AND EEOENT BEYOZOA — CANU AND BASSLER 29 



globular, transverse; it is formed by two calcareous pellicules of 



which the superior is incomplete and leaves a large frontal cicatrix. 



,, ^ r^ • 1^0 = 0.35-0.37 mm. 



Measurements. — Opesmms, ^ „^ _ „„ 



Uo = 0.20-0.32 mm. 



fL2 = 0.60-0.70 mm. 



2^°"H. = 0.30-0.35 mm. 



Affinities. — This new species differs from Alderina cesticella Canu 

 and Bassler, 1923, in its much larger zooecia and in the number of 

 its spines. The primoserial zooecia arise always from a lateral bud 

 of a zooecium, a very frequent phenomenon in the Membranipores. 

 There are, however, some species (AcantJiodesia) where the budding 

 is always distal. The nature of budding has not been sufficiently 

 studied by the zoologists, and it may perhaps furnish excellent generic 

 or specific characters. Our unique specimen does not bear avicularia. 



Occurrence. — Pliocene: Minnitimmi Creek, Bocas Island, Almirante 

 Bay, Panama. 



Hohtype.—C&t. No. 70832, U.S.N.M. 



Genus GEPHYROTES Norman, 1903 



1920. Gephyrotes Canu and Bassler, North American Early Tertiary Bryo- 

 zoa. Bull. 106, U. S. National Museum, p. 300. 



In introducing this genus into our nomenclature of 1920 we con- 

 sidered especially the spiramen which we thought corresponded to a 

 special function^. Also all the species do not have the same frontal 

 structure; often it is totally different from that of the genotype; in 

 Gejphyrotes spinosa it is identical with that in Acanthocella. If this 

 genus is indeed natural, it will be proof once more that the aspect of 

 the frontal can not furnish generic characters since it results simply 

 from the ordinary variations of the primitive spines. If we are 

 deceived in our views, it is necessary to range the species with die- 

 tellae in Crihrilina as Levinsen thought in 1909; but the conclusion 

 remains the same for Crihrilina. 



Lang, 1922, gave the greatest importance to the form and the 

 arrangement of the costules. This is not our view, for the exterior 

 ornamentation can not serve to establish a natural classification. 



GEPHYROTES SPINOSUM, new species 



Plate 4, Figure 11 



Description.— The zoarium encrusts stones. The zooecia are dis- 

 tinct, separated by a furrow, elliptical, a little elongated; the frontal is 

 convex; the costules, 16 to 18 in number, are narrow, a little distinct, 

 arranged transversely; they are separated by two or three very small 



' Moreover, we consider that the absence of dietellae is still an important difference from the group 

 Membraniporella- Cribrilina, 



