420 SYSTEMATIC PALEONTOLOGY 



S. unicornis and its varieties;, the most striking of the differences being 

 the relatively unimportant one of having much fewer avicularia. 



Occurrence. — Chesapeake Geoup. Very common at Petersburg, \'a., 

 and at localities in South Carolina. Choptank Formation ( ?). Mary- 

 land ( ?). (The specimens have been mislaid, and we cannot now verify 

 its occurrence in the state.) 



Collection. — U. S. National Museum. 



SCHIZOPORELLA SUBQUADRATA ' n. Sp. 



Plate CXIV, Fig. 1 ; Plate CXVIII, Figs. 5, 6. 



Description. — Zoarium consisting of a single layer attached to foreign 

 bodies. Zooecia subquadrate, usually about a third longer than wide, 

 averaging O.T mm. in length, arranged in rather regular radial and less 

 regular concentric rows. Surface convex, punctate. Orifice subterminal, 

 slightly transverse, enclosed by a thin peristome, widest and elevated only 

 on the lower side: notch wide, occupying about a third of the straight- 

 ened ])roximal outline of tlie orifice. Avicularia rather large, usually 

 one, rarely two, to each zooecium, situated on either side of the orifice, 

 acuminate and prominent above. 



Excepting that the oral sinus or notch is much wider than shown in 

 Eeuss' figures of his variety tetragona of S. unicornis (Johnston), *S'. siih- 

 qiiadrata agrees almost exactly with it. Our species probably should be 

 ranked as only another variety of *S'. unicornis, which as figured by 

 Hincks " agrees better in the form of the orifice with the American fossils 

 than does the Austrian variety. 



Occurrence. — Choptank Formation. Governor Run. (The label 

 showing the exact locality of tlie specimen figured has been mislaid, but it 

 is certainly from the Pliocene of the southeastern states, and probably 

 from the horizon of the Choptank formation.) 



Collections.— V. S. National Museum, Maryland Geological Survey. 



1 Compare LepraJia anmta var. tetragona Reuss, 1874, Die foss. Bry. d. Oster.-Uugar. 

 Miocans, p. 10, pi. vii, tigs. 1-3. Also ScMzoporella unicornis (Johnston) Hincks. For 

 full synonymy see Miss Jelly's Synonymic Catalogue of Marine Bryozoa. 



•-'British Marine Polyzoa, 1880, pi. xxxv, figs. 1-5. 



