-iBT. 14 FOSSIL, AND EECBNT BKYOZOA CANU AND BASSLEE 53 



Genus RECTONYCHOCELLA Canu and Bassler, 1917 



KECTONYCHOCELLA ABYSSICOLA Smitt, 1873 



Plate 5, Figures 1-3 



1873. Vincularia abyssicola Smitt, Floridan Bryozoa. Kongl. Svenska 

 Vetenskaps-Akademiens Handlingar, vol. 11, p. 6, pi. 1, fig. 61 

 (not 60). 



1881. Vincularia abyssicola Hincks, Contributions, General History of 



Marine Polyzoa. xlnnals and Magazine of Natural Historj', ser. 5, 

 vol. 7, p. 155 (sep. 42), pi. 10, fig. 4. 



1882. Vincularia abyssicola Hincks, Annals and Magazine of Natural His- 



tory, ser. 6, vol. 9, p. 85. 



1884. Smittipora abyssicola Hincks, Annals and Magazine of Natural His- 

 tory, ser. 5, vol. 13, p. 358 (sep. 114). 



1887. Smittipora abyssicola Hincks, Critical notes on the Polyzoa. Annals 

 and Magazine of Natural History, ser. 5, vol. 19, pp. 161, 164. 



1891. Onychocella abyssicola Hincks, Contributions. General History Ma- 

 rine Polyzoa, Annals and Magazine of Natural History, ser. 6, vol. 5, 

 p. 177. 



1893. Onychocella abyssicola Hincks, Annals and Magazine of Natural His- 

 tory, ser. 6, vol. 11, p. 204. 



-,, ^ ^ • |/io = 0.25-0.30 mm. 



Measurements. — Opesmmi, ^ „_ 



^ Uo = 0.25 mm. 



ry . I Lz = 0.7 5 mm. 



U2 = 0.50 mm. 



Structure. — Our specimen is incrusting, but grows into free, cylin- 

 drical stems formed of six longitudinal series of zooecia, conforming 

 perfectly thus with the specimen studied and figured by Smitt. 



The mural rim is somewhat saHent, but it is often absent, and the 

 zooecia are then separated by a furrow. The cryptocyst is convex 

 and finely granulated. The opesium is often marginated, either reg- 

 ularly elliptical or presenting only a concave proximal border. 



The onychocellarium is much smaller than the zooecia; itisogival 

 and rather irregular in its dimensions. Smitt's specimen appears to 

 bear somewhat larger onychocellaria — the only appreciable difference. 



The micrometric dimensions are quite variable. We have meas- 

 ured a large zooecium of 1.00 mm. by 0.75 mm. and small opesia of 

 0.20 by 0.15 mm. 



A small portion was covered by the ectocyst, and we were thus 

 able to prepare the opercular valve. It is exactly similar to that 

 figured for Velumella by Levinsen, 1909. The attachments of the 

 opesiular muscles are at the same place. The figure of Nordgaard 

 for Bectonychocella soUda appears to us then incomplete in its infe- 

 rior part. 



The ancestrula is small and surrounded by five very irregular 

 zooecia. 



Affinities. — This species differs from the genotype BectonycJiocella 

 soZ^(?a Nordgaard, 1907,inthepresenceof much smaller onychocellaria. 



