.MANN DIATOMS OF THE ALBATROSS VOYAi 351 



wide variety of thai Bpeciee Bui Grunow's form is in no sense Schmidt's diatom. 

 Aside from a general similarity of outline and of the median line area, the) are mosl 

 strongly contrasted. Nol only does il fail to agree in beading and the direction of the 

 striae, especially at the center, with the figure in the Atlas quoted byGrunow, fl bul 

 if we take Schmidt's original type form& the difference ie even more pronounced. 

 Grunow also includes whal Lagerstedt has perhaps erroneouslj called A. didyma 

 I Ehrenb. Kin/. 1 This form, the author says in a note, is close to one of Donkin's 

 figures of N. didyma d Bui withoul going into the meritsof Lagerstedt's identifica- 

 tion ii is enough to say thai il has little if any resemblance to either Schmidt's sub- 

 cincta or to my Bpecies, and thai subcincta is far closer to Donkin'e figure <>f didyma 

 than the one given by Lagerstedl . a fad noted under N. subcincta in this reporl . The 

 exacl type form of Schmidt's N. subcincta occurs a1 station 3008H, corresponding 

 with it in form, markings, and size. When il is compared with this species, all true 

 resemblance vanishes. Ii may be instructive to add here the measurements o 

 aow's and Schmidt's specimens for comparison with those given above. Length of 

 Grunow's largesl specimen, 0.107 mm.; smallest, 0.062 mm; of Schmidt's type, A', sub- 

 cincta, 0.054 nun. 



Type in the (J. S. National Museum, No. 590148, from station 3604, Bering 

 Augusl 12, 1895; 1,401 fathoms, bottom of green ooze. 



Navicula pleurostaurum Mann. 

 StauroneU acuta W. S. Smith, Synop. Brit. Diat. 1: 59. pi. L9./. 187, front./ 

 L853. Pritch. Hist, [nfus. ed. 4. 914. pi. ;../'. 76. 1861. Van Eeur. Synop 

 pi. .;./. •;. 1881; Treat. Diat. 159. pi. l.f. 51. L896. Grun. Denkschr. Akad. 

 Wien 48-: 47. L884. II. L. Smith, Sp. Dial . Typ. no. 485. 1874. Wolle, Diat. 

 N. A. pl.8.f. 11. 1890. Schmidt, Atlas pi. iji.f. i 5. L889. Deby, Ann. Soc. 

 Malar,,]. 15,-icr. n : 88. 187G. <'leve. Sv. Yet. Akad. Handl. 26-': 150. L8 

 Pleurostaurum acutum Rabh. Bedwigia 1: 17. pi. t.f. 11. L859. Jan. in Bedwigia 



1: 25. 1859; 5: pi. S.f. 1-8. 1863. Rabh. Fl. Eur. Alg. 1: 20. 259./. 6. L864. 

 Pleurostaurcm acutum Rabh.; De Toni, Syll. Alg. 2: 222. 1891. 

 Stauroneis hochii Pant. Beitr. Bacill. Ung. 3: pi. 6.f. 93. 1893. 

 As 1 find it necessary to discard the genus Stauroneis as separate from Navicula for 

 reasons alreadygiven, I am compelled to give a new specific name to this well-known 

 diatom. The name A", acuta is preempted by N. acuta Kiitz.. an indeterminate form,< 

 as well as N. "rum (W. Smith) O'Meara. ' 



The synonymous form Stauroneis hochii Pant, can nol be used, as there is a A 

 Pant. Q I therefore apply to this diatom the specific name pit wrostaurum, taking the 

 lapsed generic name of Rabenhorst,^of which this particular diatom was the type. As 

 Rabenhorsl has pointed out, this diatom is peculiar in the sunken stauros as well as in 

 the internal thickening of the side margins, especially toward the ends, which give a 

 thickened, hooded aspecl to the apices. De Toni and other- acci pi this as an ade- 

 quate generic distinction. I do not consider this and similar forms, as A 

 fulmen Bright., to be sufficiently distinct from other examples of Navicula to require 

 tln-ir separation. Cleve,» while retaining this in Stauroneis, makes use of Pleuro- 



"Schini.lt. Alias pi. IS. / .:/. 1875. 



bJahreeb. Komm. Deut. Meere 2: pi. l.f. 1. 1874. 



i I'.ili. Sv. Vet. Akad. Handl. 3 ; ::;<;. pi. t.f. .. 1876. 



dDonk. Brit. Diat. pi. ;../'. 8b. 1871 73. 



t Kin/. Bacill. :»:'.. pi Ml. 



./ Proc. K->y. [rish Acad. 11. 2: K)7. pi 34. / 5 



g\\xu\. Beitr. Bacill. Ung. 2: 49. pi 



» Bedwigia 1:17. 1859. 



'Sv. Vet. Akad. Handl. 26-': 150. L894. 



