GOMPHONEMA. 



269 



ANALYSIS OF SPECIES. 



* Asymmetrica Grun. Valve having a rather large isolated dot near one of the sides of the 



central nodule. 



Median strife alternately ) 

 long and short. \ 



Valve 



without a 

 hyaline 

 area, 

 slightly 

 stauronei- 

 form. 

 Median 

 stria; not 

 alternately 

 long and 

 short ; no 



large 

 rounded Valve 



hyaline having a 



area. hyaline 



area, more 



or less 



stauronei- 



form. 



L A large round hyaline area 



Valve very large, inflated at the two apices .G. geminatum. 



Valve rather small, not inflated at the lower 



apex 



Valve not 



lanceolate 



rostrate. 



r 



Upper 



apex 



apiculate. 



Upper 

 apex not 

 apiculate. 



Valve lanceolate-rostrate 



. G. constrictum. 



f Valve inflated at me- 

 dian portion . G. acuminatum. 



\ Valve not inflated at 



[ median portion . G. Augur. 



! Median portion and 



J upper apex inflated G. subtile. 



(, No portion inflated . G. montanum. 



. G. parvulum. 



At least f Valve naviculoid, with the two apices 

 one of the nearly similar . . . G. gracile. 



apices of 



jomphonemoid, with the two 



lissimilar . G. micropus. 



the valve 



subacute. 



I Valve goni| 

 I. apices di 



The two 

 apices 

 almost 

 equally 

 obtuse. 



f Valve nar- ( Valve very large, 

 row, elong- rather broad . G. Vibrio. 



ate, length -| 



6 to 8 times j Valve of medium size 



its breadth. [ or small, narrow . G. intricatum. 



Valve not very elongate, length 

 L about 4-5 times its breadth . G. angustatum. 



. G. ventricosum. 



* * Symmetrica Grun. No isolated dot ; the two sides of the valve similar, 

 ( Fresh water : Pseudo-stauros very visible ; stria; radiate '. . G. Olivaceum. 



V 



Marine : No pseudo-stauros ; striae sub-parallel 



. G. exiguum. 



/. Stri<x near the nodule alternately long and short, at least on one of the 



sides of the valve. 



G. geminatum (Lyngb.) Ag. (Syst. 1824, p. 12; w. Sm., 



S.B.D., i., p. 78, pi. 27, f. 235*), plate 29, fig. 810. 



Valve large, strongly inflated at the median portion, with apices inflated, 

 capitate ; the lower apex considerably smaller than the upper. Raphe 

 surrounded by a considerable hyaline area ; inflated round the median nodule, 

 and displaying 3 to 5 granules placed unilaterally. Transverse stria? robust, 

 9 or 10 in 1 c.d.m., strongly granular, radiate, convergent in the middle 

 of the valve, divergent towards the apices, going round the upper terminal 

 nodule, absent round the lower terminal nodule, which terminates in a smooth 



