54 
Greville^ on Aster olampr(B< 
who alone has discovered it. The gland-like pores are here 
found in a different position,, and apparently offer a good dis- 
tinguishing character. 
19. Asterolampra stellulata, n. sp. Grev. — Small; nucleus 
solid j umbilical lines thick ; segments smooth ; a gland-like 
pore exactly opposite the extremity of the rays. Diameter 
•0016". (Fig. 40.) 
Hab. Barbadoes deposit ; rare. 
In the form of the segments this minute valve is like A. 
Marylandica ; but differs essentially in every other character. 
The segments are about half the radius in lengthy and are 
quite smooth. The gland-like pore in this species is opposite 
the ends of the rays, and so close that it requires careful 
adjustment to separate them distinctly. I have only seen 
two examples, one of which has seven, the other nine rays. 
20. Asterolampra dubia, n. sp., Grev. — Small; nucleus 
solid ; umbilical lines thick, very short ; segments very large, 
smooth; bases of the rays obovate; gland -like pore con- 
spicuous, opposite the ends of the rays. Diameter '0015''. 
(Fig. 41.) 
Hab. Barbadoes deposit ; very rare. 
I have thrown together, at the close of this section, two or 
three curious and even whimsical-looking diatoms, in which 
the Asterolampoid structure can be traced, although some of 
the parts indicate an approach to other genera. In the pre- 
sent four-rayed frustule the segments are so large as to occupy 
two thirds of the radius ; and a singular appearance is pro- 
duced by the widest part of the ray being next the nucleus, 
inverting the usual order. The narrow portion is extremely 
short, and the brilliant and conspicuous gland-like pore is 
situated between the termination of the rays and the margin. 
21. Asterolampra ambigua, n. sp., Grev. — Central nucleus 
solid ; umbilical lines broad ; rays more or less cordate, the 
narrow portion sometimes undeveloped; the ray- tube very 
prominent; segments smooth; diameter '0007" to -0018" 
(Figs. 42—45). 
Var. a. Bays not prolonged; heart-shaped; three-lobed. 
(Figs. 42, 43, 44 ) 
Var. b. Bays prolonged; the bases deltoid. (Fig. 45.) 
Hab. Barbadoes deposit ; T. G. Bylands, B.K.G. 
This is one of the perplexing organisms which may be 
looked for at the confines of a group in which a singular 
variation of structure exists. I am indebted to my friend 
Mr. Bylands for the use of two drawings, from which I have 
made the figs. 42 and 44. The first represents the diatom 
in its most simple form, but whether of babyhood I cannot 
