MANN DIATOMS OF THE ALBATROSS VOYAGES. 273 



This genus and the next, Asteromphalus, form together a group Bharply defined 

 from all oilier disciform diatoms. The two genera are easil) distinguished from «m< li 

 other by the fact thai In Asteromphalus one of the radial ing limbe i- nol symmetrica] 

 wiih the rest, bul much narrower, and al its inner extremity, where il goes to make 

 ii 1 1 the central rosel te of segments, il is generally ool a£ the resl are, i. e., wedge-shaped 

 and terminating al the center, bul is either club-shaped and extended beyond the 

 center or rectangular and nol reaching the center, or if il happen to be wedge-shaped 

 it is smaller and narrower than the other segments. Although this asymmetrj of one 

 radiating limb in Asteromphalus is ver} constanl in its man) Bpecies, il i- a rather 

 inadequate basis for separal ing into i wo genera forms thai are otherwise so much alike 

 and are so di fferenl from all other diatoms. Bu1 for convenience of classification it is 

 certainly advantageous to leave them as they are. The genera Rylandsia Grev., 

 Truania Pant., Bergonia Brun, Stelladiscus Ratt., and Asterodiscus Johnst. are the 

 nearest forms to the two above-named genera. 



Asterolampra marylandica Ehrenb. Ber. Akad. Wiss. Berl. 1844: 76./. 10. L845. 



Bail. Amer. Journ. Sci. 48: pi. \.f. B. L845. Bright. Quart. Journ. Micr. Sci. 8: 



ill. pi :,./. .;. I860. Wallich, Trans. Micr. Soc. Lond. n. b. 8: 17. pi. /../'. / 



I860. Elalfsin Pritch. Hist. [nfus. ed. L836.pZ. ll.f.88. L861. Moeb. Diat.-taf. 



pi. 82. f. I ;. L890. Griff. & Henf. Micr. Diet. ed. 3. pi. 19. f. 5. L875. Grev. 



Trans. Micr. Soc. Lond. n. s. 8: L08. pi. 3. f. t \. L860; 10: 11. pi. ; . /. 1-3. 



L862. Ratt. Proc. Roy. Soc. Edinb. 16: L93. L889. 

 Asterolampra septenarius Johns. Amer. Journ. Sci. II. 13: 33. L852. 

 Asterolampra impar Shadb. Trans. Micr. Soc. Lond. n. s. 2: 17. pi. 1 . f. hj. 1854. 

 Asterolampra hexactis Ehrenb. Phys. Abh. Akad. Wiss. Berl. 1872: 392. pi. 9.f. 1-2. 



L873. 

 Asterolampra pelagica Ehrenb. Ber. Akad. Wiss. Berl. 1854: 238. L855?; Phys. 



Abh. Akad. Wiss. Berl. 1841: 2: , »l\ pi. 6./. ',. L843. 

 Found at stations 2807, 2920H, 2923, Galapagos [slands, Hawaiian [slands, and off 

 southern California. 



ASTEROMPHALUS Ehrenb. 



Asteromphalus Ehrenb. Ber. Akad. Wiss. Berl. 1844: 198, 200. 1845; Mikrog. 



pi. 35A. XXI. f. 3. 1854. Ratt. Proc. Key. Soc. Edinb. 16: 206. L889. DeTonT, 



Syll. Alg. 2: L409. L894. 

 SpatangUium Breb. Bull. See. Linn. Norm. 2: 294 7. pi. .;./. 3. L857. 

 Aetinogramma Ehrenb. Phys. Abh. Akad. Wiss. Berl. 1872: 255, 392. pi. 9.f. 3-6. 



1873. 

 Mesasterias Ehrenb. Phys. Abh. Akad. Wiss. Berl. 1872: 392. pi 9.f. 7. L873. 

 Asterolampra Ehrenb. in part; Grev. Trans. Micr. Soc. Lond. n. s. 8: 117-119. pi. 

 -',./. l. r >-lS. I860. 



The genera nearest to this are the same as are enumerated nndei Asterolampra, 

 where also the close similarity of these i wo genera i> discussed. Greville misplaced 

 nearly all his example of this genus in Asterolampra. 



Asteromphalus arachne I B re b. I Kali's in Pritch. Bist. [nfus. ed. !. 837. pi 



L861. Schmidt, Atlas pi 38./. 3 ',. L876. .Ian. Abh. Schles. Ges. Vaterl. Cult. 



1862': W.pl.iA.f. 13, pi IB. f. 16. L862. Ratt. Proc. Roy. Soc. Edinb. 16: 



665. 1880. DeToni, Syll. Alg. 2: I 117. L894. 

 Spatangidium arachru Breb. Bull. Soc. Linn. Norm. 2: 296. pl.S.f. i. L8 

 Asterolampra arachne drew Trans. Micr. Soc. Lond. n. b. 8: L23. I860. 

 Asteromphalus malleus Wall. Trans. Micr. Soc. Lend. n. s. 8: 17. pi. :./. 11. I860. 

 Asteromphalus malleiformis Wall. Trans. Micr. Sue. Lend. n. b. 8: pi. :. f. 11. expl. 



1800. 



