40 P. T. CLEVE, SYNOPSIS OF THE NAVICULOID DIATOMS. 



23. P. Griiiidleri Grun. (1880). — V. lanceolate, gently sigmoid, gradually tapering to the 

 siibacute ends. L. O, .36 to 0,46; B. 0,o6 2 to 0,o7 2 mm. Median line .slightly sigmoid, central. Transv. 

 and obl. strite "Vis ii^ t*'Oi ^^i^- — GrRUN. A. D. p. 54. Per. p. 15 Pl. VI f. I. 



Marine: Campeachy Bay (Grun.). 



This species is according to Peragallo nothing but a variety of P. rigidum. It seems me 

 to be more nearly related to P. strigosum. 



24. P. aiisti"ale Grun. (1867). — V. linear, lanceolate, sigmoid, with obtuse ends. L. 0,08 

 to 0,1 1; B. 0,0 17 mm. Median line central, sigmoid. Central nodnle large, rounded. Median strite 

 more distant tlian the terminal. Transv. stria^. 21 to 23 in 0,oi mm.; obl. strite 18 to 20 in the 

 middle and 20 to 23 in 0,oi mm. at the ends. — Grdn. Novara p. 21 Pl. I f. IS. A. D. p. 51. 

 Per. IV f. 24 to 27. P. cestuarii var. Cl. D. of Java II f. 19. P. ceqiiatoriale Cl. M. I). N:o 145, 

 146, 1878. P. inflatum Shadb. T. M. S. II p. 16 Pl. I f . 9 (1854)? 



Marine (2}elagic): Balearic Islands! Siimatra! Java! New Zealand (Grun.). 



P. australc is very nearly connected with P. naviciilaceuni and with P Xormanii. 



25. P. Noruiiinii Ralfs (1861). — V. gently sigmoid, lanceolate, Avith subacnte ends. L. 0,i3 

 to 0,22; B. 0,027 to 0,036 mm. Median line sigmoid, central. Transv. strite 19 to 21 in 0,oi mm. 

 Obl. stritE 17 to 18 in the middle and 20 to 21 in 0,oi mm. at the ends. — Ralfs in Pritch. Inf. 

 p. 919. P. affine Grun. A. D. p. 51 (1880). V. H. Syn. Pl. XVIII f. 9. Per. IV f. 5, 8. P. aftine 

 var. Norm. Per. IV f. 6, 7. 



Marine: Spitsbergen! Davis Strait! North Sea! Mediterranean Sea! Red Sea! Java! Sumatra! 

 Samoa! Atlantic coast of North America! Colon! 



Var. fossilis Grun. (1880). — L. O, i.^ to 0,22; B. 0,o3 to 0,035 mm. Transv. stritc 17 in_0,oi 

 mm. Obl. strice 13 in the middle and 16 to 17 in 0, 01 mm. at the ends. — P. affine var. fossilis 

 Grun. A. D. p. 51. Per IV f. 16 to 18. P. virginiacum H. L. Smith (accord. to Perag.). P. (estuarii 

 var. intermedia Grun. Novara p. 102. P. ueogradense Pant. III Pl. XXI f. 315 (1893)? 



Marine (fossil): Virginia! Nankoori (Grun.). 



Var. marylandica Grun. (1880). — Rhomboidal-lanceolate, acute. L. 0,24 to O.28; B. 0,03 to 

 0,044 mm. Transv. striiB 14 to 18 in 0, 01 mm. Obl. stritB 13 to 17 in 0, 01 mm. in the middle 

 and closer at the ends. — P. affine var. maryl. Grun. A. D. p. 51. Per. p. 10 Pl. IV f. 15. 



Marine (fossil): Nottingham, Maryland! 



P. Normanii is one of the most comnion species, and connected with P. australc and P. stri- 

 gosum, wliich latter has the same shape, and from which it may be distinguished by its median 

 oblique strife, which cross each other at the angle of 90° and become acuter towards the ends. It 

 would be advisable to unite into one species P. naviculaceum, P. australc and P. Normanii. Peragallo 

 mentions a form called P affine var interrupta (Pl. IV f. 1, 2) which has an excentric median line. 

 This form, as well as the specimen lig. 4, seems to me to lae more akin to P. dccoruni var. dalmaticum. 



26. P. aiiguliitum Quekett (1848). — V. rhomboidal-lanceolate, angular in the middle, with 

 acute ends. L. 0, 17 to 0,36; B. 0,036 to 0,05 mm. Median line central, slightly sigmoid. Central 

 nodule small, rhombic. Transv. and obl. striaj equidistant 18 to 22 in 0, 01 mm. Angle 60°. — 

 Navic. angulata Quek. on the microscope p. 438 Pl. VIII f. 4 to 7 (according to W. Sm.). F.angu- 

 latum W. Sm. B. D. I p. 65 Pl. XXI f. 205. V. H. Syn. p. 115 Pl. XVIII f. 2 to 4. Per. V f. 3 

 to 5. Nav. Thuringiaca Ivutz. (according to Grunow). 



Marine: North Sea! Barbados! 



Forma undidata Grun. (1880). V. with slightlj' undulate margins. — Grvn. A. D. p. 51. 

 Per. Pl. V f. 6. 



Marine: Bohuslän, Sweden! Belfast (Per.). 



