Mr. H. J. Carter on the Polytremata. 197 



structure a fusiform, nodose, calcareous spicule, of a deep purple 

 colour, from a Gorgonia projects from one of the apertures 

 (fig. 6, (i)y while in this and another aperture a globo- 

 stellate, from a compound tunicated animal, may be observed 

 (fig. 6, ?•?•). So there may not only be spicules of different 

 sponges incepted, but a heterogeneous assemblage of all kinds 

 of minute objects. 



As regards the heterogeneous assemblage of minute crude 

 material about the dried pseudopodia, the like may be observed 

 to occur, for the most part, in the bodies of all the genera of 

 Rhizopoda mentioned at the commencement of this communi- 

 cation, disappearing only in the frustules of the Diatomaceas, 

 where, however, there would still appear to be a " minute 

 pore opening into the interior" of the " large granules," as 

 on the surface oi Aulacodiscas formosus noticed by Mr. Kitton 

 (Monthly Microscop. Journ., June 1873, pi. xx. fig. 2), but 

 which does not admit nourishment except under the most 

 attenuated form. 



Again, although the inception of heterogeneous material is 

 evident in the Polytremata, it is not so in most of the other 

 known Foraminifera ; and the only species of Radiolaria in 

 which (in the dead tests) I have seen it is a Haliomma shaped 

 like a gourde-de-pelerin [Lagenaria), dredged up plentifully 

 with the sponge RosseUa &c. in 300 fathoms, 741° south lat. ; 

 so that this may have been a -post mortem occurrence, although 

 the contents closely resemble those of the Polytremata and 

 those in the tests of living Difflugia and Euglypha. 



Colour. Although I have never met with a colourless spe- 

 cimen of Polytrenia miniacexim^ or one that did not present 

 the appearance of red or pink coral, especially after getting old, 

 it is often accompanied by small patches of foraminated cells 

 or chambers (varieties of our British species Planorlndina 

 vidgaris)^ which as often present alight brick, roseate, or vio- 

 laceous hue as they are absolutely colourless. Why the colour 

 should be constant in Polytrema miniaceum and not so in these 

 patches of cells, I am not able to explain ; but among the sand 

 accompanying the sponges dredged up on board H M.S. ' Por- 

 cupine ' in the Atlantic Ocean, around tlie north of Ireland and 

 Scotland respectively, it is not uncommon to find a Globigerine 

 test {Sphceroidina?) presenting this colour, although I have 

 never met with even a fragment from there of Polytrema 

 miniaceum. The older the Polytrema appears to be, the deeper 

 is the colour ; and, as with the roseate patches of Pla7iorbulina, 

 the last-formed portions appear to be the lightest. 



Thus Polytrema miniaceum externally differs from all other 

 known Foraminifera in presenting a fixed, calcareous, arbo- 



