.MANN DIATOMS OF THE ALBATROSS VOYAi Z7v 



farther apart than else\* here, giving to the interspace the appeal brighl nar- 



row ring; processes two or thre< stout, spherical, placed ;ii about one-sixth a radius 

 from the margin; the base of each Burrounded by a small hyaline area, from which an 

 obscure hyaline li ixtends to the center; border very narrow, minutely beaded. 



Diameter of \ ah e 0.065 to 0. L33 mm. 



Type in the U. S. National Museum, No. 590131, from station L505H, Santa Cruz 

 Light-house, Monterej Baj . < al. L904; L0 fathoms. 



The concentric beading of this species reminds one of . 1. brou nil Norm., though it 

 is much more pronounced here. The species di Efers from A. brownii in the com 

 of the valve, the character of the processes, the border, etc. The latter is also a much 

 more delicate species i nan i his massh •■ one. 



Although Rattray has used the above specific name for an Actinocyclus, I have 

 applied il here because it is bo aptly descriptive of this diatom's most striking 

 characteristic. 



Tripodiscus cosniiodiscus Maim. sp. nov. I'i n LIV, FIG! RE 4. 



Valve circular, nearly flat, beaded; beading minute, closely and evenly set in 

 radiating lines, excepl where these lines are Blightly bowed around the twelve some- 

 what protuberant portions of the valve bearing the twelve | no hyalim 

 tral area : margin obscure; each of the tweh e processes consist ing of a prolongal ion of 

 a single row of beads, this within one-sixth a radius of the margin becoming a narrow 

 hyaline ridge crowning the twelve slightly protuberanl portions of the valve and ter- 

 minating in an igly small but evidently Bpherical process. Aspect of the 

 valve somewhat like Greville's Cosmiodiscus barbadeni 



Diameter of valve, 0.095 mm. ; beads L30to L35 in 0.1 mm. 



Type in the U. S. National Museum, No. 590132, from station 4029H, Bering Sea, June 

 27, L900; 913 fathoms, bottom of gray sand and clay. 



Tripodiscus kinkeri I Schmidt .Mann. 



Aulacodiscus kinkeri Schmidt. Atlas pi. 106. f. 4-5. l v 



Aulacodiscus margaritaceus kinkeri Ratt. Journ. Hoy. Micr. Soc. 8 1 : 352. 1888. 



The dominant form of the presenl genus is probably to be Been in A. margar I 

 Ralfs; and under that specific name Rattray has grouped a host of forms con-: 

 as separate species by other author.-.' 1 ' This condensation was much needed, and has 

 been well done. Bui in a few instances i1 seems to have been carried too Ear. The 

 above case is an example. Schmidt's species has a Btrong general resemblance to 

 both .!. margaritaceus Ralfs and A. crux Ehrenb.; but I think to make it a variety 

 is hardly justified. Schmidt's form is a far flatter specimen than Ralfs As 



the di fference between varieties and species is pract ically a thing of personal opinion, 

 the recognition of Schmidt's species is simply an expression of the fact that I look upon 

 it as a justified expedient for distinguishing between this form and others that are 

 called A. margaritaa us Ralfs. It may nol be oul of place hero to add that the multi- 

 plication of named varieties is, I think. to»be avoided when ble. A- a rule 

 if a new form is so different from an already existing S] | uire taxonomic 

 recognition, it is safe to look upon il as a ies. The gradations of the diatoms 

 are almost limitless, and named varieties be multiplied ad libitum. In this 

 work I have omitted these whenever possible and have added none to the lisl myself. 

 The remark.- on this Bubjecl by Hew William Smith'' are worthy of consideration. 



Found at station 3696, off Bonshu fsland, Japan. 



Tran-. Micr. Soc. Lond. n. s. 14: 79. pi. ?./ /:. L8l 

 b Journ. Roy. Micr. Soc. 8': 351. L888. 

 ■ Quart: Journ. Micr. Sci. 3: L30 135. I 



31713- vol l". ft 5 "7 5 



