RUTILARIA. 



433 



GENUS 101. RUTILARIA (Grev., 1863). Emend Grev., 



1866. 



Frustules very compressed, united 

 in a short filament. Valves gently 

 elevated at the angles, with a peculiar 

 central nodule prolonged into two 

 short, linear, obtuse processes. Mar- 

 gins of valve pectinate, ciliate. 



Fig. 156. Rutilaria {Epsilon 

 var.) tenuicornis. 



This curious genus includes about a 



dozen species, mostly fossil. The figure 

 in the text (fig. 156) represents R. {Epsilon var.) tenuicornis Gr//n., found in a 



living state at Manilla. 



GENUS 102. CLAVULARIA 

 GREV., 1865. 



Frustules free, linear, elongated, with 

 numerous transverse divisions, an elevation at 

 the median portion and numerous awns. 

 Valves linear, dilated at the median portion, 

 shewing somewhat scattered awns on the 

 surface. 



A single species, Clavularia Barbadensis Grev., 

 found by C. Johnson in the Cambridge Deposit, 

 Barbadoes (fig. 157). 



This curious form disconcerts all preconceived 

 ideas, and it is difficult to know where to class it. 



In the specimens in my possession, the valve is 

 smooth and shows no trace of striation ; the spines 

 are not situated in a straight line, as in Greville's 

 drawing, whose figure we reproduce, but they are 

 scattered on the valve. 



We give below the description which Greville 

 made of C. Barbadensis. The examination of my 

 specimens, which are unfortunately few in number, 

 suggests a doubt if C. Barbadensis be a true 

 diatom. 



The following is Greville's description : 



" Frustule '0060" to 0080" in length and 

 scarcely "0002" in breadth, perfectly linear, except 



E E 



Fig- 157- 



Clavularia Barbadensis. 



