the " Cirri pede " Plumul ites. 127 



longitudinal fold so characteristic of the ' outer plates of 

 Plumulites. 



Plumulites esthonicus appears to agree most closely with 

 P. rastritmn, Moberg (1914 P- 493, figs. 7, 8), from the 

 Ordovician {Rastrites skiffei-) of Sweden, and P. peachi, 

 Nicholson & Etheridge (l^^O; P- 301, pi. xx. figs. 8-10; 

 also Reed, 1908, p. 519, pi., figs. 1-5), from the Upper 

 Ordovician (Ardmillan Series) of Scotland. From P. ras- 

 tritum it difl'ers in the admedian plates by the more 

 rounded and protuberant inner lobe, and in the outer 

 plates by the longitudinal fold being nearer to the outer 

 margin instead of to the inner margin. From P. peachi 

 the admedian plates differ in having the inner lobe more 

 protuberant, the margin being more fully rounded to the 

 apex, and in the outer plates the growth-lines of the outer 

 lobe are more regularly curved and consequently the outer 

 })ioximal angle is more regularly rounded ; the growth-lines 

 are more closely disposed, and none of the known plates 

 attain to more than one-third the size of the largest-known 

 plates of P. peachi. 



Works quoted. 



Bassler, R. S. 1911. "The Early Palaeozoic Brvozoa of the Baltic 



Provinces." Bull. 77, U.S. Nat. Miis. pp. xxfii, 382, 13 pis. 

 Bekker, H. 1919. "New Bryozoa from the Kuckers Stage in 



Esthonia." Ann. & Mag. Nat. Hist. (9) iv. pp. 327-335. 

 BoNNEMA, J. H. 1909. " Beitrag zur Kenntnis der Ostrakoden der 



Kuckerschen Schicht (C")." Mitth. Miner.-Geol. lust, lleichs.- 



Uuiv. Groningen, ii. pt. i. pp. 84, 8 plis. 

 KoKEN, E. 1897. "Die Gastropoden des baltischen Untersilurs." 



Bull. Acad. Imp. Sci. St. Petersb. (v.) vii. no. 2, pp. 97-214. 

 Moberg, J. C. 1915. "Nja bidrag till kannedomen om Sveriges 



silurcirripeder." Geol. Foreu. Stockholm Forhandl. xxxvi. 



rift. vi. pp. 485-495, text-figs. 1-12. 

 Nicholson & Etheridge. 1880. Mouogr. Silur. Foss. Girvau, 



p. 301, pi. XX. figs. 8-10. 

 Reed, F. R. C. 1908. Trans. Roy. Soc. Edin. xlvi. pt. iii. no. 21, 



p. 619, pi., figs. 1-5. 

 Schmidt, F. 1881. "Revision der ost- baltischen silurischen Trilo- 



biten . . ." Abth. 1. M^m. Acad. Imp. Sci. St. Petersb. (7) 



XXX. no. 1, pp. 237, 16 pis. 

 Schmidt, F. 1882. " On the Siliu-ian (and Cambrian) Strata of the 



Baltic Provinces of Russia as compared with those of Scandinavia 



and the British Isles." Quart. Journ. Geol. Soc. London, xxxviii. 



pp. 514-536. 

 Withers, T. H. 1915. "Some Palfeozoic Fossils referred to the 



Oirripedia." Geol. Mag. pp. 112-123, text-figs. 1-7 (p. 114). 



