\l\\\ DIATOMS Of I IN. ALBATROSS VOYAGES. 261 



pose. Kiitzing, Greville, and Brightwell, however, ignored thislattei tnd so 



perpetuated ili«' error. In addition to the confusion between Mi«- above-mentioned 

 genera, there is a second reason for the difficulty here encountered, and one thai parti) 

 explains the other; the inconstant and rather trivial generic distinction between this 

 and Coscinodiscue Ehrenb. The general structure and markings are th — of the lattei 

 genus, and the one striking distinguishing feature, the "pseudonodule"* of Actinocy- 

 clu8, is unquestionably very inconstant. Some species, like .1. pyrotechnicus Deby, 

 seem fairly well marked and Btable; bul many others differ from well-known species 

 of Coscinodiscus only in the presence of this pseudonodule, and il isnol unusual to find 

 specimens both with and withoul this structure in ih<- same gathering. Thus C. cur- 

 vatulu8 Grun., is .1. curvatulus Jan., withoul its pseudonodule; 90 also C. subtilis 

 Ehrenb. and .1. subtilis Greg., C./uscus Norm., and .1. ral/sii W. Smith Ralfs, ( . 

 tuberculatu8 Grey . , and -4. sparsus Greg.) Ratt.; while in II. L. Smith's type slide no. 

 12 the form he calls " . Ictinocyclus ini< rpunctalus Bright.," is uniformly lacking*in the 

 pseudonodule and agrees exactly with his type slide no. 421, marked "Podosira 

 maxima Grun." There mighl be mentioned a third reason for the difficull character 

 of this genus, namely, the Lack of u r '""l literal ure on the subject and especially of good 

 figures of the Bpecies. Rattray's revision of Actinocyclus contains some excellent 

 work, bul ii leaves much to be desired. Too many old specific names have been dis- 

 turbed; the illustral ions are scanty and too small* and the analytical key is most diffi- 

 cult to use. Schmidt's Atlas has so far practically ignored this much needed sub- 

 ject, an undertaking of far more importance to the science than the wearisome 

 reillustration of species already repeatedly figured in its plates. 



Actinocyclus alienus < rrun. : Van Heur. Synop. pi. 125. /. 10, 12. 1881. Ratt.Journ. 

 Quek. Micr. Club [1.4:144. L890. Wolle, Dun. X. A. pi. 85. /. 1 ,:. 1890. DeToni, 

 Syll. Alg. 2: L165. 1894. 



The specimens found by me agree with whal Grunow calls variety cali/omicab 

 which is the type of the species. 



Found al station 3361H, off the coast of Alaska. 



Actinocyclus crass is (W. Smith) Van Heur. Synop. pi. 124. J 6,£ l s M. DeToni, 

 Syll. Alg. 2: I Hi!), is'.) I. 

 Eupodiscus crassus W '. Smith, Synop. Brit. Dial. 1:24. pi. ,./. \1. li 

 Actinocyclus subcrassus Ratt. Journ. Quek. Micr. Club II. 4: L54. l x '»" 

 Actinocyclus circumdatus Pant. Bacill. Ung. 1: 66. pi. S.f. 28. I sv 7 



Van Beurck's figure is hardly typical, as the beading is radially arranged in the 

 type. Rattray's proposition to make a new species of the nonradial forms is, how- 

 ever, ii"i i" be commended. They should be looked upon as varieties of ih<- above. 



Found ai Btation 3346, off the coasl of Washington. 



Actinocyclus curvatulus Jan. ; Schmidt, Atlas pi. 57./. SI. I s 7v Wolle, Diat. V \ 

 pi. 94./. U. 1890. 

 ( 'oscinodiscus cun atulus subou limns Grun. Denkschr. Akad.Wien48-:83. pi. \.f .15. 



1884. 

 Actinocyclus subocellatus Ratt. Journ. Quek. Micr. Club II. 4: 145. 1890 



The above differs merely in its pseudonodul l Grun., c 



a difficulty thai < rrunow tries to avoid by making this species a form as \ ariet y subon I- 

 latus of that Bpecies 



Found at station 2807, Galapagos Islands. 



a Journ. Quek. Micr. Club [1.4: 137 212. pi. 11. 1890. 

 '< Van Heur. Synop. 125. pi. 25 

 ( Schmidt. Atlas 57./. •■■ . lx s . 



