Aug. 1, 1S67.] 



HARDWICKE'S SCIENCE-GOSSIP. 



181 



Cymbclla Ehrenbergii (Kiitzing). Valves cymbi- 

 form ; the median line sub-central, with central and 

 terminal nodules. Strife distinct, costate (fig. 1SS). 



Cymbclla cuspidata (Kiitzing). Valves with the 

 extremities produced and slightly acuminate. Striae 

 obscurely moniliform (fig. 190). 



Fig. I8y. 



Fig. I S3. 



Gomphonema acuminatum (Ehr.). Frustule 

 stipitate. Valve with central inflation, triangular 

 and apiculate above, attenuated below, with median 

 line, and central and terminal nodules. Stria? 

 conspicuous, moniliform. Variety (3, much elongated 



(fig. 191). 



Gomphonema capitatum (Ehr). Valve slightly 

 constricted towards the upper extremity, which is 

 somewhat rounded ; much attenuated towards the 

 lower, which is slightly acute. Stria; distinct, 

 moniliform (fig. 192). 



Cocconeis Thwaitesii (Smith). Valve slightly 

 constricted towards the obtuse apices. Median line 

 sigmoid. Stria; very faint. I refer the form in 

 this deposit to this species with some hesitation as 

 it differs in some degree from the form described in 

 the " Synopsis of British Diatomacese." 



Odontidium Tabellaria (Smith). The figures 

 (183, 185, 186, 181) are considered by Dr. Lewis 

 to be sporangial states of this species. They are 

 common in the lighter part of the Monmouth 

 deposit. 



Eig. 182 represents the valve of a minute form 

 considered by Dr. Lewis to be an abnormal state of 

 Tetracyclus. The absence of the frustules from the 

 deposit renders it impossible to decide as to the 

 correctness of this view. 



Eig. 189 represents a valve of Pinnularia gigas. 

 This fine form has not, 1 believe, ever been figured 

 in any English work on the Diatomacese. 



Eunotia hemicyclus (figured at page 133, fig. 146) 

 has been found by Dr. Lewis growing like Syncdra 

 lunaris, the frustules attached to a fixed point, and 

 he has removed it to that genus. A curious 



abnormal variety may occasionally be detected in 

 the deposit — it has an angular central inflation on the 

 inner margin of the valve. 



This enumeration of forms found in the Monmouth 

 deposit, commenced at page 133, continued at page 

 156, and now terminated, must not be regarded as a 

 complete catalogue of the Diatoms to be found in 

 it. There are several species which I could not 

 satisfactorily refer to any forms previously described, 

 and I do not feel myself warranted in describing as 

 new species forms occurring in a fossil deposit. 



Fig. 190. 



W 



Fig. 191. 



Fig. 189. 



Fig. 192. 



In conclusion, it is with pleasure that I publicly 

 tender my thanks to the Rev. E. C. Bolles for his 

 kindness in forwarding this deposit to the Editor for 

 distribution amongst the students of Diatomaceas in 

 Great Britain, hoping that his example may be 

 followed by others in respect of deposits of a similar 

 character from other and little known localities. 



Norwich. E. Kitton- 



