6 The Rev. W. Smith on the Diatomacese. 



regarded as necessarily implying an important difference in in- 

 ternal structure, the circumstances alluded to do not seem a 

 sufficient ground of exclusion, and it would perhaps be as well to 

 allow Campylodiscwi to include all those species with equidistant 

 valves to which its veiy significant name can with propriety be 

 applied. • 



Campylodiscus costatus, mihi. Valves orbicular, costse distinct, 

 radiate, about 44, centre of the disc smooth or minutely punc- 

 tate. Average diameter of valve -^j-^ of an inch {v. v.). 



A freshwater species. Living : river Froome near Dorchester, 

 ]\Iay 28, 1849. Bramley springnear Guildford, J. R. Capron, Esq. ! 

 Fossil, in deposit from Lough Mourne, co. Antrim, Ireland, described 

 in 'Ann. Nat. Hist.' for February 18.50. In deposit at Peterhead, 

 Aberdeenshire, described by Dr. Dickie in 'Ann. Nat. Hist.' for 

 August 1848 ! 



This species approaches C. radiosus, Ehr., figured by Kiitzing 

 in his "^ Bacillarien,' tab. 28. fig. 12, but differs from it in the 

 number of its costse, which in C. radiosus reach seventy. The 

 costse in the latter are also, according to Kiitzing's figure, much 

 shorter than in the present species. 



In my paper on the Lough Moui-ne deposit I have named this 

 species C. noricus, Ehr., and it may possibly be identical with 

 that species ; but in the absence of any figure I am unwilling to 

 decide positively, and shall on this and other occasions prefer 

 giving a new specific name rather than run the risk of creating 

 confusion by trusting to a verbal description merely. 



Plate I. fig. 1 a. C. costatus with the disc of valve turned towards the 

 eye ; b, view showing the edge of frustule and connecting membrane. 



Campylodiscus spiralis, mihi. Valves elliptical. Frustule twisted 

 so as to present a spiral outline ; costse distinct, about sixty, 

 parallel or slightly radiate ; centre of the disc smooth or mi- 

 nutely punctate. Average length of valve ^fo ^^ ^^ inch, 

 average breadth of ditto ^^^ {v. v.). 



SurireUa S2nralis, Kiitz. ? Bacill. p. 60. tab. 3. fig. 64 ; Species Al- 

 garum, p. 34. 



In a spring near Bramley, Guildford, mixed with Navicula attenuata 

 and other Diatomacese, J. R. Capron, Esq. ! 



This beautiful species so closely resembles the figure of Suri- 

 reUa spiralis given by Kiitzing, that I have ventured to adopt 

 his specific name. The frustule ordinarily presents an outline 

 exactly resembling the figure 8 with flattened ends ; this arises 

 from the twist or contortion of the valves being so considerable 

 that the edge of the frustule is found on the widest part, and is 



