Observations on British ZoophyteSr 217 
reptile Plesiosaurus. But in others the homomorphism is 
so perfect, that animals belonging to the lower class were 
long confounded by the most eminent zoologists with those 
of a higher class. Thus, various species of the i^om- 
menifera were classed amongst the Cephalopoda. The 
shells of many of the Foramenifera are, indeed, exact 
copies of those of Cephalopoda, both recent and fossil. 
The recent Nautilus and Argonaut, and the fossil Bacu- 
lite, Orthoceratite, Hamite, and Ammonite, find their 
representatives in the microscopic Ntimulina, Polystomella, 
Dentalia, Cristellaria, and Rotalina. The shells of the for- 
mer are inhabited by the highly organised cuttle-fishes ; 
those of the latter by creatures which can scarcely be said 
to possess any organization. The chambers of their shells 
are filled with a glairy living mass, which streams like a 
fluid in and out through the innumerable minute pores with 
wdiich the shells are pierced. The streams unite together 
to form widely-spread meshes and expansions, which en- 
velope, absorb, and digest smaller living beings coming in 
contact with them, and on which the animals move, or 
rather flow along. But although the forameniferous ani- 
mal is a mere fluid mass, destitute not only of organs and 
stomach, but even of the simplest cellular structure, it is 
yet capable of exercising the most important functions of 
life — motion, nutrition, and reproduction, — and of erecting 
for itself edifices mathematically correct in design, which 
arrest the eye by their exceeding beauty of form and orna- 
mentation, and which, deserted by their tenants through 
successive ages, have formed no inconsiderable part of the 
solid frame-work of our globe. A curious instance of "ho- 
momorphism" occurs in the subject of the present notice, 
Ophryodendron abietina, which is fashioned after the type 
of Sipunculus Bernhardi, a highly organised Echinoderm. 
This animal consists of a shapeless oblong mass, immove- 
ably fixed to the corallum of Sertularia pumila. From one 
end of the mass arises a closely wrinkled proboscis, sur- 
mounted by a tuft of short tentacles. The proboscis can 
be entirely withdrawn into the body, or extended to an as- 
tonishing length, until it appears as a clear glassy wand, 
