Dec. 1861.] 



Narrikal or Cochin Mud Bank. 269 



FAMILY XVI. — CYMBELLEiE. 

 Genus CYMBELLA (Ag. Kutz,) 

 Cymbella Ehrenberghii, (Kutz.) 

 C. — — maxima (Nag,) 

 Genus AMPHORA (Ehr.) 

 Amphora costata, (Sm.) 

 A- — spectabilis (Greg.) 

 Genus GOMPHONEMA (Ag.) 



Gomphonema (? Sp.) I cannot identify this with any described 

 species, but as I have not seen a front view I leave it unnamed. It 

 is very like some Naviculeae, but as the two halves of the valve 

 differ in form it is undoubtedly a Gomphonema. Its moniliform 

 striation is beautifully distinct. 



FAMILY XVIII.— NAVICULE^E. 

 Genus NAVICULA. (Bory, Rab.) 

 Navicula didyma (Ehr. Kutz.) 



N Hennedyi (Sm.) 



N— birostrata (Greg.) 



N— — rhombica (Ehr.) 

 N formosa (Greg.) 



N- distans (Sm.) Pinnularia distans. S. B. D. 1. P, 56. 



P. 18.169. 



N elliptica (Kutz.) 



N — patula (Sm.) 



N rectangula'a (Greg.) 



N firm a. (Kutz.) 



N — - cyprinis 



N Castorii. N. S. (J. M.) valve broadly elliptic with sub- 

 acute extremities, twice as long as broad, striae, moniliform, parallel, 

 23 in. 1.1000", not quite reaching the median line ; a small smooth 

 transverse median fascia ;— median line somewhat curved near 

 the extremities, length 1.370". 



1 have dedicated this fine spices to Captain Castor the Master 

 Attendant at Cochin, to whom we are indebted for the knowledge 

 of this extensive deposit. 



N— — — (? Sp.) Valve rhomboido — lanceolate, with a scarcely 

 perceptible contraction near the broad rounded extremities. Striae 



