268 DISCOVERY REPORTS 



Cells discoid, solitary. Valves almost flat. Central area occupying about one-third of 

 the total diameter of the valve surface. Central area furnished with usually five or six 

 short lines which furcate to produce a number of curved veins. These veins proceed one 

 to each punctate sector, and vary in number from twelve to sixteen. Narrow hyaline 

 rays proceed radially from the central area towards the periphery where they terminate 

 in a short rounded process, dividing the peripheral area into sectors. Sectors punctate, 

 puncta fine, usually arranged in fascicules of parallel lines. Puncta of uniform size 

 throughout the whole valve-surface. Chromatophores, numerous rounded bodies. 

 Diameter of valve 80-1 20/x. 



This species is widely spread throughout European waters, but was observed at one 

 station only on the 30th W meridian. Probably oceanic ; never found in great numbers. 



Observed at St. 684. 



Asterolampra marylandica Ehrenberg. 



Ehrenberg, 1844, p. 76. 

 Hustedt, 1929, p. 485, fig. 271. 

 Asterolampra septenaria Johnson, 1852, p. 33. 

 Asterolampra impar Shadbolt, 1854, p. 17, pi. 1, fig. 14. 



Cells discoid, solitary small. Valves almost flat, slightly undulated. Central area large, 

 usually occupying one-half to three-fifths of the total diameter of the valve surface. 

 Central area furnished with radiating lines. Lines straight, usually six to eight in 

 number. Each line proceeds to the apex of a peripheral punctate sector. Short hyaline 

 rays proceed from the central area to the periphery dividing the peripheral area into 

 sectors. Sectors rounded, obtuse, finely punctate towards the margin of the valve. 

 Puncta increase in size slightly towards the apex of each sector. Puncta arranged in 

 irregular tangential lines. The marginal line of puncta towards the valve centre of each 

 sector is usually larger than the others, and appears to be more prominent. The puncta 

 in this marginal line are subrectangular. Chromatophores: few large irregular bodies. 

 Diameter of valve 64-70/x. 



This diatom has a wide distribution throughout subtropical seas, and is very common 

 in fossil material obtained from the eastern seaboard of the United States of America. 

 The specimens observed in the Atlantic Ocean from a line of Stations along the 30th 

 W meridian, were remarkably regular in size and possessed usually seven rays. Some 

 specimens with six rays were observed, but only four with eight rays. An oceanic 

 species favouring a high salinity. 



Observed at Sts. 424, 425, 675, 677, 681, 684, 687, 690, 1575. 



Asterolampra Vanheurcki Brun. 

 Brun. 1891, p. 10, pi. 14, fig. 1. 

 Cells discoid, flat. Valves divided into seven equal sectors by narrow rays radiating 

 from a small central area. Central area traversed by seven simple radiating lines. 

 Sectors covered with very fine punctation. The marginal line of puncta of each sector is 

 stronger than the others, giving the sectors clear definition. The narrow ray terminates 



