184 Mr. H. J. Carter on Melobesia unicellularis, 



ever, some doubtful organisms to be worked out. The Textu- 

 laria alluded to is a stout arenaceous variety, frequently Bi- 

 generine in its mode of growth, and with an anomalous aper- 

 ture, sometimes labyrinthic, but more frequently consisting of 

 two or three distinct circular pores. Mr. John Young, of 

 Glasgow, has a number of beautiful specimens of this form ; 

 and I find, in my notes on his collection of Carboniferous 

 Foraminifera, that I have the MS. name Textularia antiqua 

 appended to it. 



EXPLANATION OF PLATE XII. 



Fig. 1. A piece of *SVrcmm7?u«fi-limestone from Elfhills, natural size. 

 The upper portion of the figure shows a weathered surface, the 

 lower a fresh fracture. The white spots on the latter indicate the 

 tufts of crystals which often occupy the interior of the chambers. 



Fi(f. 2. Polytlialamous specimens of Saccamminn Carteri, natural size. 



Fiys. 3 & 4. Broken specimens showing the occasional labyrinthic struc- 

 ture of the inner surface of the test and the ci-ystalline calcareous 

 masses occupying the interior. Fig. 3 magnified 10 diams.^ 

 fig. 4 magnified 15 diams. 



Fig. 5. Transparent section of a segment, infiltrated partially with carbo- 

 nate of lime, partially with silica : o is a lobe of colloid silica. 

 Magnified 29 diams. 



Fig. G. A portion of the last specimen, at a, more highly magnified, 

 showing the structure of the infiltrated test in transverse section. 

 Magnified 80 diams. 



XXII. — On Melobesia unicellularis, letter Jcnoion as the 

 CoccoUth. By H. J. Caetee, F.E.S. &c. 



Foe some time past I have frequently noticed a cell in 

 connexion with minute fragments of marine Sponges and 

 Compound Ascidia3 obtained from the Laminarian zone here 

 (Budleigh-Salterton) which have been placed under the mi- 

 croscope for examination, also among the calcareous stellates 

 (spicules) of the latter which have been mounted in Canada 

 balsam ; and I have as often resolved to endeavour to know 

 more about its history when opportunity offered. 



Meanwhile, having been in London in April last, I then 

 procured, through the kindness of my friend Dr. Carpenter, a 

 little of the deep-sea mud from the bed of the Atlantic Ocean, 

 to see what the coccolith was, of which I had previously read 

 Prof, Huxley's excellent account in the ^ Quarterly Journal of 

 Microscopical Science ' (No. 32, Oct. 1868), and immediately 

 recognized in the coccoliths present in this mud facsimiles of 

 the " cell " above mentioned. 



Not content, however, witli Prof. Huxley's analysis or his 

 conclusions, as I could not divest myself of the idea which this 



