74 o'mearA; ox diatom ace^. 



difFerent Algce. The dredge was thrown into water of some 

 seven or eight fathoms' depth at low water, and dredged 

 along into water of such a depth that the boat would just 

 float. I brought the material thus gathered to the hotel for 

 the purpose of searching it over for minute Crustacea, Anne- 

 lids, &c., &c. ; and being struck on several occasions, when 

 examining it with a low power (li objective) of the micro- 

 scope for Foraminifera, with the number of Diatoms present, 

 I dried the weed in the sun, and then shook off" all or the 

 greater part of the fine particles adherent to it. This 

 siliceous dust I gave to you. I also brought a small basket- 

 ful of the weed with me to Dublin, and having steei:)ed it for 

 some hours in about two quarts of distilled water, I filtered 

 it gradually through a muslin strainer, and gave you a 

 bottleful of finely divided mud that passed through. One 

 very small stream of fresh water flowed into this bay, a fact 

 that may account for the presence of fresh-water forms in 

 the Arran gathering. I feel very certain that all the Diatoms 

 were attached to the Algse, and were not taken on the ground, 

 as, OAving to the quantity of sea-weecl, the dredge did not 

 scrape the bottom. — Ever very sincerely yours, Edw, Per- 

 civAL Wright, Lect, on Zoology Dub. University." 



It will, doubtless, seem strange to most readers that Mr. 

 Kitton should have ventured to pronounce his judgment on 

 the forms referred to without having had an opportunity of 

 examining them. Had he vouchsafed to ask, I would have 

 gladly supplied him with some of the material, and then he 

 would have been in a better position to form a judgment, and 

 more weight would attach to his opinion. 



I cannot forbear to express the surprise I experienced on 

 the perusal of his paper to find that one so sharp to detect 

 what he regards as the mistakes of otherS;, and so forward to 

 expose them, should himself have been guilty of such in- 

 accuracies as the following — inaccuracies I cannot attribute 

 to any other cause than a hasty and superficial perusal of the 

 papers he undertook to criticise. 



" NavicuJa peUucida, O'M., fig. 2, is a state of Navicida 

 Pandura of De Brebisson." In my paper, N. 'pellucida is 

 fig. 3, and to it his observations are utterly inapplicable. I 

 suppose he intended to refer to iV. denticulata, fig. 2^ wliich 

 does exhibit some general resemblance to N. Pandura, 

 thougli at the same time the difference is so marked and so 

 constant, as not only to justify but as I think to require 

 a distinct name. 



Again, " Raphoneis Jtburmca, O'M., fig. 8." In my paper 

 this form is referred to in the following terms : — Raphoneis 



