50 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
shaped masses one to four inches in length. They are temporarily 
submerged in salt water, and may afterwards have to undergo desicca- 
tion for weeks or months. They may be regarded as forms of Meyenia 
Jluviatilis, of which species there may be a number of varieties ; the 
specimens in question were remarkable for an unusual abundance of 
gemmules. Mr. Potts also gives an account of a new species of Spon- 
gilla — S. Wagneri — clearly allied to the cosmopolitan S. lacustris ; it is 
to be distinguished on the grounds that it was found incru sting such 
marine organisms as barnacles and the calcareous tubes of Serpulse, and 
from the “ unprecedented multitudes of its dermal spicules.” It has the 
singular habit of hiding away its gemmules within the barnacle or among 
the convoluted stems of the Serpulm ; the spicules of the gemmules are 
more like those of S. fragilis than those of S. lacustris. 
Two New British Sponges.^ — Mr. R. Hope describes two new species 
of British Sponges. 3Iicrociona strepsitoxa was found on the flat valve 
of a Pecten ; of the microsclera the toxa is twisted in a manner quite 
unknown in other species of the genus. The other new form, which 
receives the specific name echinata, is referred with some doubt to the 
genus Trachytedania of Ridley. 
Protozoa. 
Fresh-water Heliozoa.t — The first part of Dr. E. Penard’s memoir 
deals, as may be supposed, with Actinophrys sol. He does not believe 
that the contractile vacuole communicates with the exterior, and brings 
forward facts in support of his contention. The pseudopodia have a 
very difiereut structure from those of Heliozoa with an external skeleton ; 
in the latter they are formed by extremely long and delicate filaments 
of the same thickness throughout, and not provided with any rigid 
internal support, while in Actinophrys there is a rigid axial rod and a 
finely granular layer of protoplasm. This protoplasm is derived from 
that of the ectosarc, and varies in quantity from one moment to another ; 
the axial filament is almost always invisible ; it is remarkable for some- 
times dissolving completely, and that by a process which is difiScult to 
ascribe to anything else than the will of the animal. 
As a rule, Actinophrys is immobile, or moves very slowly ; if, however, 
it is stimulated by a bright light, it moves much more rapidly. Although 
it always surrounds its prey by a layer of protoplasm, the manner in 
which it captures it varies with the size of the animal. If it be very 
small, a piece of very clear and very delicate protoplasm is rapidly 
produced from the ectosarc and takes the form of a wide-necked urn ; 
this curves round and then completely incloses the prey, which is 
gradually drawn into the ectosarc. 
If the prey be larger, say a free Vorticella striking against the pseudo- 
podia, the Vorticella contracts and the pseudopodia which are in contact 
with it become amoeboid and draw it towards the ectosarc, while the 
Actinophrys begins to surround the prey with its own substance in the 
form of a spider’s web. While this is going on, processes of the ectosarc 
mount around the Vorticella, using the base of the nearest pseudopodia 
* Atm. and Mag. Nat. Hist., iv. (1889) pp. 333-42 (1 pi.). 
t Arch, de Biol., ix. (1889) pp. 123-83 (2 pis.). 
