EAELY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 73 



PROTOCRISmA EXIGUA Ulrich. 

 Text fig. 17. 



Protocrisina exigua Ulrich, Geol. Surv. Illinois, vol. 8, 1890, p. 405, pi. 29, figs. 



4r-4c; pi. 53, figs. 11-lle; Zittel's Textbook of Paleontology (Eng. ed.), 1896, p. 



262, text fig. 417. — Cumings, Amer. Journ. Sci., ser. 4, vol. 20, 1905, pi. 7, 



fig. 53. 

 Crisinella ceilensis Wiman, Bull. Geol. Inst. Univ. Upsala, vol. 5, pt. 2, 1902, p. 



181, pi. 6, figs. 12-16. 



In the small bryozoan fauna described by Wiman from drift bowl- 

 ders of the Borkholm formation is a species, Crisinella ceilensis so 

 similar to the American Protocrisina eiigua that I am forced, even in 

 the absence of specimens, to consider them synonymous. Tlie 

 figures of both ITlrich's and Wiman's species are reproduced here, 

 and show at a glance their practical identity. Indeed, the only dif- 

 ference to be observed is that Wiman has omitted the small pores on 

 his figure of the noncelluliferous side, although he shows them dis- 

 tinctly on the other face. These pores are so easily overlooked that 

 their omission is probably due to faulty observation rather than to 

 real absence. 



The original description of Protocrisina exigua is as follows: 



Zoarium ramose; branches slender 0.6 mm. wide, 0.3 to 0.45 mm. thick, dividing 

 dichotomously at a very acute angle at intervals varying from 2 to 7 mm. Cel- 

 luliferous side strongly convex, smooth, with four, occasionally only three, series 

 of zooecia. Reverse faintly convex, flattened or slightly concave in the central part, 

 finely striate, the strige often minutely granulose. Zooecia subtubular, thin-walled 

 within, with prominent tubular mouths. Apertures subcircular, 0.09 mm. in diameter, 

 5 or 5| in 2 mm. vertically; arranged in oblique rows. A small number of circular 

 pores, 0.04 mm. in diameter, are scattered over both the reverse and cellulif erous faces. 



Occurrence. — Common in the Fernvale shales of the Kichmond 

 group in Illinois and other States where these strata outcrop. The 

 European examples were obtained from drift bowlders of the Bork- 

 holm limestone (F2) at Ojle Myr, island of Gothland. 



Specimens from American localities are in the collections of the 

 United States National Museum and the British Museum. 



PROTOCRISINA ULRICHI, new species. 

 Plate 12; text fig. 18. 



Zoarium of ramose, slender branches, averaging 0.4 mm. in width, 

 dividing dichotomously at rather regular intervals of about 4 mm. 

 and at an angle averaging 35°. Cellulif erous side slightly convex, 

 with two rows of c^uite regularly arranged zooecia, noncelluliferous 

 side smooth and flattened w^ith a distinct sulcus along its mid-length. 

 Zooecial apertures oval, 0.15 mm. in their longer diameter, arranged 

 alternately in distinct diagonal and also longitudinal rows; measur- 

 ing longitudinally, 5 to 6 zooecia in 2 mm. The accessory pores are 

 extremely small, circular to elongate, and are abundant on both sides 



