2 68 



GOMPHONEMA. 



A. minuta Cleve, (Syn. of the Nav. Diat., p. 21, pi. i, f. 7-8*), 

 plate 29, fig. 809. 



A. Amphitritis Castr. (Diat. e Dalm.c. icone; Perag Diat. Villefr., 

 p. 85, pi. 2, i. 18, and pi. 5, f. 41). 



Characters of the genus. Valve face with ventral margin arcuate, slightly 

 constricted in the median portion with a submarginal raphe edged with a row 

 of beads, abruptly depressed opposite the median nodule. Ventral margin 

 concave, smooth as far as a very conspicuous line which connects the two 

 terminal nodules, which are elongated, narrow. Striae en the valve face, 

 radiate, bifurcating several times, 16 in 1 c.d.m. Length of valve, 8 to 10 

 c.d.m. Breadth, 6 c.d.m. 



Marine. Lesina, Adriatic (Castracane). Yillefranche Bay, Mediterranean Sea (Peragallo). 

 Balearic Isles (Cleve ! ). 



Tribe hi. Gomphoneme.e. 



j Frustules curved in girdle view ; nodule or concave valve 

 { All other forms ..... 



. Rhoicosphenia. 

 . Gomphonema. 



GENUS 27. GOMPHONEMA AG., 1824. 



Valve naviculoid, asymmetrical, one of the apices 

 narrower than the other and cuneate. Frustules 

 cuneate in valve view. Parasitic, sessile or stipitate, 

 sometimes enveloped in a mucous mass. Endochrome 

 formed of a single lamina, which rests at the centre 

 on one of the sides of the connecting zone, and covers 

 the two adjacent valves and the other side of the 

 zone, on the middle of which is found the line of 

 separation. 



Prof. Cleve dismembers the genus Gomphonema, and 

 separates from it three species (G. Herculanum, mamilla, 

 and cltgans) to constitute his genus Gomphoneis. These 

 three species have, as common characteristics, transverse 

 costae, between which is found a double row of small 



alternating beads (as in N. Smithii, etc.), and traversed by a marginal sulcus, 



more or less distinct. 



Fig. 58. 



Gomphonema gemi- 

 natum. 



