270 iNTRIBUTIONS PROM l ill NATIONAL HERBARIUM. 



grouping Heliopelteac," in which is also included Polymyxus Bail., a genus which I 

 ihink hae • lo» i affinity \\ iih \ 



Tli- original union of Actinoptychus and \< tinocyclus bj Ehrenberg and the sub- 

 sequent separation of the former by the creation of thai genus in 1839 hae been dis- 

 : under Actinoeyclus It may be well to quote here the original Ehrenberg 

 distinction between the i wo as if is given by .1. \V. Bailej '■ "Under the new genua 

 Actinoptychus are now placed th"~ of the old genus Actinocyclus which pos- 



sess interna] partitions or folds, while und< i the old name are retained those in which 

 the externa] rays are not connected with interna] fold* 



Actinoptychus alternans Mann, sp. nov. Plat] XLV, FIGURE 1 



Valves circular; divided into 16 alternating segments, 8 of which bear each i 

 minute rounded process close to the margin, its base not surrounded bj a hyaline 

 these segments evenly marked with minute rows of beads, parallel to the cen- 

 tral i'"\\ or rows; thai is, nol radially arranged ; numberofrows per segment, L4orl5; 

 the s segments alternating with these without processes, marked with much 

 larger beads regularly placed in diagonal parallel rows; inner ends of these segments 

 ■ ding Blightly farther toward the center than those bearing processes, and hence 

 giving a Btellate appearance to the hyaline median area; the ••Menial ends of these 

 segments showing a uam >\\ hyaline band next to the rim; rim narrow, hyaline. 



Diameter of valve, 0.0357 to 0.0450 nun. 



The genera] aspect is similar to minute forms of .1. vulgaris Schmidt and to .1. leu vi- 

 gatus Grun., forma parva. c !i is also apparently 1 i 1< « • the rather obscure unnamed 

 figure^ which Grove rightly considers to be different from I. elegans Kali's 



Type in the U. S. National Museum, No. 590125, from station I516H, Gulf of Cali- 

 fornia, December 22, 1904; L,627 fathoms, bottom of volcanic sand, obsidian, and 

 fragments of < rlobigerim*. 



Also a variety of the above, in which the segments bearing processes are underlain 

 with secondary markings of coarse, bead-like dots irregularly disposed. 



Pound a i stations 2690H, between < California and the Hawaiian [slands, and L516H 

 in the South Pacific. 



Actinoptychus grundleri Schmidt, Alias pi I./, a. L875; />/. 90. / :. pi 100. / •-' ;. 

 L886. Pant. Beitr. Bacill. (Jng. I: pi 12./. 106. L887. 



My specimen differs from the type in that the hyaline Bpaces between the outer 

 extremities of the segments are nol united by thin hyaline bands parallel t<> the margin. 



Found ai station 2835, off Lower California. 



Actinoptychus janischii Grun.; Van 1 1 cur. Synop. />!. 122. / 6. 1881. Schmidt, Alias 

 r l. 158. f. 8 10. 21. L890. Pant. Beitr. Bacill. LTng. 1: pi 16./. 148. L887. De 

 Toni, Syll. Alg. 2: L388. L894. 

 Halionyx vicenarius Jan. Abh. Schles Ges. Vaterl. Cult. 1862': 10. />!. /../'. '.. L862 



The above specific name of Janisch, though older than I. janischii, was preempted 

 by Actinoptychus vicenarius Ehrenb.,< a decidedly different diatom, without pro< 

 a iul having no hyaline lines bisecting i In- segments. 



Pound ;ii stal ion 2823. 



"The Lens 1: 8, 17. 1872. 

 b \m. Journ. Sci. 46: 300. 184 l. 

 ■ Schmidt, Atlas pi I \2./. 15. L890. 

 ^Schmidt, Ulas, pi 158./ ;. L890. 



« Phys. Abh. Akad. Wiss. Berl. 1841: HO. L843. Ehrenb. Mikrog. pi 18 

 l B5 I . 



