K( 



)N(iL. SV. VKT. AKADKMIENvS HANDLINCiAR. BAND 26. N:() 2. 48 



the ends. Central area rather hirge, irregularly rliomljoid. Transv. and obi. strite 'Vi.-,7 'Vio' "/u' 

 *" IS' "*;i<) i'l ^''^' i""i- — ^^- flKadratum rut:':' rhonibcum (jRUN. A. 1). p. ')(). P. rhomh. Per. Ill 

 f. 13. U. 



Marine: Java! Labnan! Port Jackson! Aukland ((4ruii.), Samoa! China! Oakland. California! 



F. r//(i»ih('i(iii greatly resembles F. quadntfiiiii and atifjulalntn, l)ut differs by the more ex- 

 centric median line and the coar.ser striation. 



36. P. obsciiruni A\'. Sm. (1852). — V. narrow linear, with unilaterally narrowed and 

 rounded ends. L. 0,o9 to 0, !.->; B. 0,oi mm. Median line strongly asymmetrical, near the ends 

 close to the curved margin. Transv. and obi. stripe equidistant, 25 (Per.) to 29 (W. Sm.) in 0,0 1 

 mm. — W. Sm. Ann. M. Nat. H. [2] IX p. 8 PI. 1 f. 11. B. D. I p. 65 Pi. XX f. 206. Per. 1 

 f. 14, 15. F. madlentnm Per. p. 13, PI. V f. 24 (1891). 



Marine: England (W. Sm.), Balearic Islands (Per.). 



Var. harhadcnsis Cl. L. 0, i4 to 0,i8; B. 0,oi.t mm. Transv. and o1)l. strife '9/20' ""/21 

 in 0,01 mm. 



Marine: Barbados! 



37. P. (Rlioicosigiiia) falcatum Douk. (1861). — V. linear, with unilaterally narrowed and 

 rounded ends. L. 0,i5 to 0, is; B. 0,oi.5 mm. Median line flexuose in the middle, strongly ex- 

 centric, following the curved margins of the ends. Stria; fine, oblique. — Donk. M. J. I p. 7 PI. I 

 f. 1. Mhoic. falcat. Grun. Hedw. VI p. 20 (1867). Per. IX f. 25, 27. 



Marine: Northumberland (Donk.). 



Doubtful; specimens in Grove's collection are Gyrosigma ardicum Cl. 



38. P. (Rhoicosigma';:') iiicertiim Per. (1S91). — V. slender, sigmoid, acute. L. 0,:!3; B. 

 0,01 'J mm. Median line slight^ sinuose, very excentric towards the ends. Transv. and obi. strite 

 '".j in 0,01 mm. - Per. p. 32 PI. IX f. 21. " 



Marine: Atlantic coast of North America! 



39. P. (Rhoicosigma) Wcissflogii (tRUN. (18H0). — V. linear, with unilaterally narrowed 

 and rounded ends. L. 0, 118 to 0,1.34; B. 0,oi8 to 0,oi',) mm. Median line excentric, and strongly 

 sigmoid, closely following the curved margins for a considerable distance. Median oblique stria; 

 cross each other in an angle of 90"; the terminal more acute. Transv. and obi. .stri;p '-',- in 0,oi 

 mm. - EJioic. Wehsfl. Crun. A. D. p. 54. Per. IX f. 23, 24. 



Marine: Seychelles (V. H. coll.)! 



40. P. umbilicatuin C'l. N. Sp. — V. linear, with unilaterally rounded and very slightly 

 rostrate ends. L. 0,ob.-) to 0,10; B. 0,oi5 mm. Median line strongl}' sigmoid, for a long di.stance 

 closely following the convex margin of the valve. Central area unusually large, transverse and 

 rounded. Transv. and ol)l. striiE equidistant, 22 in 0,01 mm. — PI. IV f. 22. 



Marine: Labuan! 



This species is in form nearest to P. Wcissflogii, but differs by the large area, and the 

 close striation. 



41. P. Exsul (.'l. N. Sp. -- V. linear-lanceolate, gently sigmoid, with subacute ends. L. 0,i8; 

 B. 0,0 18 mm. Median line strongly sigmoid and excentric, enclosed between two longitudinal lines. 

 Central nodule small, rounded. Tran.sv. and obi. stricE -723 in *^)<Ji mm- — I*l- IV f. 17. 



Marine: Gulf of Naples (Deby Coll.)! 



This species, of which I have seen only one specimen, has the outline of P. formosKDi, but 

 has much closer striation, and longitudinal lines close to the median line. 



