Observations on British Zoophytes. 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 Fora- 

 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 Numulina, 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 

 which 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 ce ho- 

 momorphism" occurs in the subject of the present notice, 

 Ophryodendron abietina, which is fashioned after the type 

 of Sipunculus Bernhardt, 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 be entirely withdrawn into the body, or extended to an as- 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, 



