the " Cirri pede " Plumdites. 127 



longitudinal fold so characteristic of the outer plates of 

 Plumulites. 



Plumulites esthonicus appears to agree most closely with 

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

 Urdovician [Rastrites skiffer) of Sweden, and P. peachi, 

 Nicholson & Etheridge (1880, p. 301, pi. xx. figs. 8-10; 

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

 Ordoviciau (Ardniillan Series) of Scotland. From P. ras~ 

 tritmn it differs in the adniedian 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. ptachi 

 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 

 proximal 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 . ijeaclii. 



Works quoted. 



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



Provinces," Bull. 77, U.S. Nat. Mus. pp. xxiii, m-1, 13 pis. 

 Bekkke, II. 1919. "New Bryozoa from the Kiifkers Stage in 



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

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



Kuckerschen Schicht (C^)." Mitth. Miner.-Geol. Inst. Eeichs.- 



Univ. Groningen, ii. pt. i. pp. 84, 8 pi?. 

 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. "N^'a bidrag till kannedomen cm Sveriges 



silurcirripeder." Geol. Fijren. Stockholm Forhandl. xxxvi. 



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

 Nicholson <& Etheridge. 1880. Mouogr. Siliir. Foss. Girvan, 



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

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



p. 519, 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 Silurian (and Cambrian) Strata of the 



Baltic Provinces of Russia as compared with those of Scandinavia 



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



pp. 514-536. 

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



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



