BRITISH DIATOMACE^. 77 



Genus 25. DORYPHORA, Kiitz. 



Frustules stipltate, lanceolate, or elliptical ; valve with a median line ; 

 nodules obsolete. 



Distinguished from the last by the median line dividing the valve 

 into two symmetrical parts, and by the absence of distinct nodules. 

 The second species, upon Avhich the genus has been founded by Pro- 

 fessor Kiitzing, has been seen by him in its living state, attached by 

 a short stipes to larger Algae. I have only found it in my gatherings 

 after the frustules have become detached from their filaments ; but 

 the first species has occurred to me abundantly in a living state, and 

 I have been able to refer it with confidence to the present genus, to 

 which it is more closely allied than to Cocconema, with which genus 

 writers have hitherto classed it. 



1. Doryphora Boeckii, W. Sm. F. V. lanceolate, obtuse; V. lan- 

 ceolate, acute; striae moniliform, 24 in •001". Length '0026" to 

 •0053". v.v. 



Cocconema Boeckii, Ehr. Inf. xix. 5. Kiitz. Bacill. vi. 5. Quek. H. C. xii. 7. 

 Marine. Poole Bay, Mar. 1849, W. Sm. 

 Plate XXIV. 223. 



2. Doryphora Amphiceros, Kiitz. V. orbicular, elliptical, or ellip- 

 tical-lanceolate ; striae moniliform, 18 in "OOl". Length •0012" to 

 •0033". v.s. 



Kiitz. Bacill. v. 10. xxi. 2. Prit. Anim. xvii. 21. Rhaphoneis, Ehr. in Bail. 

 Sound. 61 -Go. 



Marine. Poole Bay, Sept. 1851, &c., TF. Sm. River Thames, Mr. Shad- 

 bolt. Near Ipswich, Mr. Hodgson. 



Plate XXIV. 224. a' and a", outlines of other forms. 



Genus 26. GOMPHONEMA, Jff. 



Frustules stipitate, cuneate ; valves variable in outline, striated, with 

 a median line and nodules at centre and extremities. 



The cuneate form of its frustules, arising from the unequal develop- 

 ment of the connecting-membrane, distinguishes Gomphonema from 



