D4: BRIGHTWELL, ON RHIZOSOLENIA. 
2. Rh. pileolus. A doubtful species. 
3. Rh. campana, Bermuda. No figure is given of this; but 
from the description it appears to be a terminal section of a 
Rhizosolenia. 
4, Rh. calyptra, South Sea. This is clearly the calyptri- 
form terminal process of a Rhizosolenia, very like our Rh. 
styliformis. 
5. Rh. ornithoglossa. The terminal process of the same 
species. Of Bailey’s Rh. hebetata we were favoured with 
specimens by the late lamented professor. It is clearly dis- 
tinct from any of the above, and from any of our species. — 
We present the following as a synopsis of the species 
which have come under our observation. 
RHIZOSOLENIA. 
Filamentous, frustules subcylindrical, greatly elongated, 
silicious, marked by transverse lines, extremities calyptri- 
form, pointed with a bristle. 
Species. 
1. Rh. styhiformis——Frustules from six to twenty times 
longer than broad ; transverse lines obvious ; terminal process 
at the base spathulate and bifid; straw colour to chestnut 
brown. 
“Found in the stomach of an Ascidia taken from oyster 
shells, dredged twenty or thirty miles from the Yorkshire 
coast, at a place a little to the north of the Humber, known 
as the ‘Silver Pit?” (Mr. Norman, of Hull, in ‘ Annals 
Nat. Hist.,’? vol. xx, p. 158). In Noctiluce, Gorleston, 
Suffolk. (Col. Baddeley.) In guano, Callao, often in 
little bundles of fragments. In Salpe. (Dr. Wallick). 
The base of the calyptriform process is carried out into a 
spatula-formed elongation, bifid at the end; the lines of the 
bifid division run upward on either side, with a stout nerve, 
to nearly the apex of the cone. Boiled in acid, the frustules 
break up, and the calyptriform processes in an isolated but 
perfect state, and detached imperfect rings are only to be 
found. (Pl. V, fig. 5.) 
2. Rh. imbricata.—Frustules four to seven times longer 
than broad, punctated; terminal process subulate, entire; 
pale straw colour. 
In Ascidiz with the former. (Mr. Norman.) In Nocti- 
lucee. (Col. Baddeley.) 
The direction of the transverse lines and puncta give this 
species an imbricated appearance. (Pl. V. fig. 6.) 
